In this Letter we investigate the possible emission of low-energy electron neutrinos and electron-positron pairs of anomalously large multiplicity in close-to-central $pp$ collisions at LHC. The scenario is based on confining SU(2) Yang-Mills dynamics of Hagedorn temperature $\sim m_e=511 $keV being responsible for the emergence of the lightest lepton family and the weak interactions of the Standard Model. Although cut off by LHC's detectors these electrons-positron bursts would be seen indirectly by a large defect energy and thus an anomalously strong decrease of events with interesting high-energy secondaries for increasing $\sqrt{s}$ . This is because the formation of superconducting (preconfining) SU(2) hot-spots `steals' a large fraction of $\sqrt{s}$ subsequently transferring it to a thermal spectrum of electron neutrinos, electrons, and positrons liberated through evaporation. We thus propose the detection of electrons and positrons of kinetic energy $\sim m_e$ and photons of energy $\sim 2 m_e$.
The non-radiative scattering amplitudes for electron-positron annihilation into quark and lepton pairs in the TeV energy range are calculated in the double-logarithmic approximation. The expressions for the amplitudes are obtained using infrared evolution equations with different cut-offs for virtual photons and for W and Z bosons, and compared with previous results obtained with an universal cut-off.
A recent observation of the 511 keV electron-positron annihilation line from the Galactic bulge has prompted a debate on the origin of the galactic positrons responsible for this emission. Assuming equilibrium between annihilation and injection of positrons in the Galaxy, we investigate the possibility that positrons were produced by past gamma ray bursts (GRBs). We compare the positron annihilation rate inferred from the observed 511 keV line with the predicted injection rate due to electron-positron pairs leaking out of individual GRBs and those pairs produced by GRB photons in the dense mol…
The Geminga pulsar has long been one of the most intriguing MeV-GeV gamma-ray point sources. We examine the implications of the recent Milagro detection of extended, multi-TeV gamma-ray emission from Geminga, finding that this reveals the existence of an ancient, powerful cosmic-ray accelerator that can plausibly account for the multi-GeV positron excess that has evaded explanation. We explore a number of testable predictions for gamma-ray and electron/positron experiments (up to ~100 TeV) that can confirm the first "direct" detection of a cosmic-ray source.
We investigate the TeV-scale stringy signals of the four-fermion scattering at the electron-positron collider with the center of mass energy 500-1000 GeV. The nature of the stringy couplings leads to distinguishable asymmetries comparing to the other new physics models. Specifically, the stringy states in the four-fermion scattering at the leading-order corrections are of spin-1 and 2 with the chiral couplings inherited from the gauge bosons identified as the zeroth-mode string states. The angular left-right, forward-backward, center-edge asymmetries and the corresponding polarized-beam asymme…
We propose several novel scenarios how capture of small sublunar-mass primordial black holes (PBHs) by compact stars, white dwarfs or neutron stars, can lead to distinct short gamma-ray bursts (sGRBs) as well as microquasars (MQs). In addition to providing new signatures, relativistic jets from these systems will accelerate positrons to high energies. We find that if PBHs constitute a sizable fraction of DM, they can significantly contribute to the excess observed in the positron flux by the Pamela, the AMS-02 and the Fermi-LAT experiments. Our proposal combines the beneficial features of astr…
We consider theories where lepton flavor is violated, in particular concentrating on the four fermion operator consisting of three electrons and a tau. Strong constraints are available from existing searches for tau -> eee, requiring the scale of the contact interaction to be less than ~(9 TeV)^-2. We reexamine this type of physics, assuming that the particles responsible are heavy (with masses greater than ~TeV) such that a contact interaction description continues to be applicable at the energies for a future e+e- collider. We find that the process e+e- -> e tau can be a very sensitive probe…
We studied the dimension-6 leptonic anomalous gauge couplings in the formulation of linearly realized gauge symmetry effective Lagrangian and investigated the constraints on these anomalous couplings from the existed experimental data including LEP2 and $W$/$Z$ boson decay. Some bounds of $O(0.1-10){\rm TeV}^{-2}$ on four relevant anomalous couplings are given by the Z factories. We studied the sensitivity of testing the leptonic anomalous couplings via the process $e^+e^-\rightarrow W^+W^-$ at future $e^+e^-$ linear colliders. We discussed different sensitivities to anomalous couplings at pol…
The influence of the electron spin degree of freedom on nonperturbative electron-positron pair production by high-energy proton impact on an intense laser field of circular polarization is analyzed. Predictions from the Dirac and Klein-Gordon theories are compared and a spin-resolved calculation is performed. We show that the various spin configurations possess very different production probabilities and discuss the transfer of helicity in this highly nonlinear process. Our predictions could be tested by combining the few-TeV proton beam at CERN-LHC with an intense laser pulse from a table-top…
Recently the DArk Matter Particle Explorer (DAMPE) has reported an excess in the electron-positron flux of the cosmic rays which is interpreted as a dark matter particle with the mass about $1.5$ TeV. We come up with a leptophilic $Z'$ scenario including a Dirac fermion dark matter candidate which beside explaining the observed DAMPE excess, is able to pass various experimental/observational constraints including the relic density value from the WMAP/Planck, the invisible Higgs decay bound at the LHC, the LEP bounds in electron-positron scattering, the muon anomalous magnetic moment constraint…
We propose that a nearby gamma-ray burst (GRB) or GRB-like (old, single and short-lived) pulsar/supernova remnant/microquasar about 10^{5-6} years ago may be responsible for the excesses of cosmic-ray positrons and electrons recently observed by the PAMELA, ATIC/PPB-BETS, Fermi and HESS experiments. We can reproduce the smooth Fermi/HESS spectra as well as the spiky ATIC/PPB-BETS spectra. The spectra have a sharp cutoff that is similar to the dark matter predictions, sometimes together with a line (not similar), since higher energy cosmic-rays cool faster where the cutoff/line energy marks the…
The rise in the cosmic-ray positron fraction measured by the PAMELA satellite is likely due to the presence of astrophysical sources of positrons, e.g. pulsars, on the kpc scale around the Earth. Nevertheless, assessing the properties of these sources from the positron data requires a good knowledge of the secondary positron component generated by the interaction of cosmic rays with the interstellar gas. In this paper, we investigate the impact of the spectral hardening in the cosmic-ray proton and helium fluxes recently reported by the ATIC2 and CREAM balloon experiments, on the predictions o…
It has long been suggested that nearby pulsars within $\sim 1 \,{\rm kpc}$ are the leading candidate of the 10-500 GeV cosmic-ray positron excess measured by PAMELA and other experiments. The recent measurement of surface brightness profile of TeV nebulae surrounding Geminga and PSR~B0656+14 by the High-Altitude Water Cherenkov Observatory (HAWC) suggests inefficient diffusion of particles from the sources, giving rise to a debate on the pulsar interpretation of the cosmic-ray positron excess. Here we argue that GeV observations provide more direct constraints on the positron density in the Te…
It was recently shown that left-right symmetric models for elementary particles can be built with only two Higgs doublets. The general consequence of these models is that the left and right fermionic sectors can be connected by a new neutral gauge boson $Z'$ having its mass as the only additional new parameter. In this paper we study the influence of the fundamental fermionic representation for this new neutral gauge boson. Signals of possible new heavy neutral gauge bosons are investigated for the future electron-positron colliders at $\sqrt s = 500$ GeV, 1 TeV and 3 TeV. The total cross sect…
Recent observations have detected extended TeV gamma-ray emission surrounding young and middle-aged pulsars. The morphology of these "TeV halos" requires cosmic-ray diffusion to be locally suppressed by a factor of ~100-1000 compared to the typical interstellar medium. No model currently explains this suppression. We show that cosmic-ray self-confinement can significantly inhibit diffusion near pulsars. The steep cosmic-ray gradient generates Alfven waves that resonantly scatter the same cosmic-ray population, suppressing diffusion within ~20 pc of pulsars younger than ~100 kyr. In this model,…
The Fermi-LAT detects no significant anisotropy of the cosmic-ray (CR) electrons and positrons ($e^-+e^+$) with seven years of data, which provides the strongest restriction to the $e^-+e^+$ anisotropy up to now. As next generation CR observatory, HERD is expected to have a better capability of anisotropy detection than Fermi-LAT. In this paper, we discuss several models aimed to explain the AMS-02 data by the present and future anisotropy measurements. We find that the upper limits of Fermi-LAT disfavor Vela SNR as the dominant source in sub-TeV, while other cases that remain safe under the c…
The DArk Matter Particle Explorer (DAMPE) is a satellite-borne, high-energy particle and $γ$-ray detector, which is dedicated to indirectly detecting particle dark matter and studying high-energy astrophysics. The first results about precise measurement of the cosmic ray electron plus positron spectrum between 25 GeV and 4.6 TeV were published recently. The DAMPE spectrum reveals an interesting spectral softening around $0.9$ TeV and a tentative peak around $1.4$ TeV. These results have inspired extensive discussion. The detector of DAMPE, the data analysis, and the first results are introduce…
We suggest that white dwarf (WD) pulsars can compete with neutron star (NS) pulsars for producing the excesses of cosmic ray electrons/positrons observed by the PAMELA, ATIC/PPB-BETS, Fermi and HESS experiments. A merger of two WDs leads to a rapidly spinning WD with a rotational energy comparable to the NS case. The birth rate is also similar, providing the right energy budget for the cosmic ray electrons/positrons. Applying the NS theory, we suggest that the WD pulsars can in principle produce electrons/positrons up to 10 TeV. In contrast to the NS model, the adiabatic and radiative energy l…
The possibility of a scalar messenger that can couple the Standard Model (SM) to a hidden sector has been discussed in a variety of contexts in the literature in recent years. We consider the case that a new scalar singlet charged under an exotic spontaneously broken Abelian gauge symmetry mixes weakly with the SM Higgs resulting in two scalar mass states, one of which has heavily suppressed couplings to the SM particles. Previous phenomenological studies have focussed on potential signatures for such a model at the Large Hadron Collider (LHC). However, there are interesting regions of the par…
For contact-interaction searches at the Linear Collider, we discuss the advantages of polarizing both the electron and the positron beams as compared with polarizing only the electron beam. In particular, for the processes e^+e^-\to μ^+μ^-, τ^+τ^-, b\bar{b} and c\bar{c} at a future e^+e^- collider with \sqrt{s}=0.5 TeV we derive model-independent bounds on the four-fermion contact interaction parameters from studies of the helicity cross sections.
Protons accelerated in the internal shocks of a long duration gamma ray burst can escape the fireball as cosmic rays by converting to neutrons. Hadronic interactions of these neutrons inside a stellar wind bubble created by the progenitor star will produce TeV gamma rays via neutral meson decay and synchrotron radiation by charged pion-decay electrons in the wind magnetic field. Such gamma rays should be observable from nearby gamma ray bursts by currently running and upcoming ground-based detectors.
Core collapse of massive stars resulting in a relativistic fireball jet which breaks through the stellar envelope is a widely discussed scenario for gamma-ray burst production. For very extended or slow rotating stars, the fireball may be unable to break through the envelope. Both penetrating and choked jets will produce, by photo-meson interactions of accelerated protons, a burst of neutrinos with energies in excess of 5 TeV while propagating in the envelope. The predicted flux, from both penetrating and chocked fireballs, should be easily detectable by planned cubic kilometer neutrino telesc…
At energies above a few TeV, no measurements of the cosmic-ray electron spectrum exist yet. By considering the similarity of air showers induced by electrons and gamma rays as seen by ground-based arrays, we use published limits on isotropic gamma-ray fluxes to place first constraints on the >10 TeV electron spectrum. We demonstrate that, due the proximity of known sources, the flux of such electrons (and positrons) can be large. We show how these smoothly connect to lower-energy positrons measured by PAMELA and relate to exciting new indications from Fermi.
Two important features of TeV-scale radiative seesaw models, in which tiny neutrino masses are generated at the quantum level, are an extended scalar (Higgs) sector and the Majorana nature. We study phenomenological aspects of these models at the ILC. It is found that the Majorana nature of the models can be tested directly via the electron-positron and electron-electron collision experiments.
The detection of GRB 180722B and GRB 190114C in sub-TeV gamma-rays has opened up a new window to study gamma-ray bursts in high energy gamma-rays. Recently it is shown that the synchrotron and inverse Compton processes are responsible for the production of these high energy gamma-rays during the afterglow. Here, for the first time we demonstrate that, the photohadronic scenario which is successful in explaining the multi-TeV flaring in high energy blazars is also applicable for gamma-ray bursts. We show that the sub-TeV spectra of GRB 190114C and GRB 180720B are due to the interaction of high …
Mirror matter models have been suggested recently as an explanation of neutrino puzzles and microlensing anomalies. We show that mirror supernovae can be a copious source of energetic gamma rays if one assumes that the quantum gravity scale is in the TeV range. We show that under certain assumptions plausible in the mirror models, the gamma energies could be degraded to the 10 MeV range (and perhaps even further) so as to provide an explanation of observed gamma ray bursts. This mechanism for the origin of the gamma ray bursts has the advantage that it neatly avoids the ``baryon load problem''…
Gamma-ray bursts (GRBs) are rare but powerful explosions displaying highly relativistic jets. It has been suggested that a significant fraction of the much more frequent core-collapse supernovae are accompanied by comparably energetic but mildly relativistic jets, which would indicate an underlying supernova--GRB connection. We calculate the neutrino spectra from the decays of pions and kaons produced in jets in supernovae, and show that the kaon contribution is dominant and provides a sharp break near 20 TeV, which is a sensitive probe of the conditions inside the jet. For a supernova at 10 M…
Some recent experiments detecting very high energy (VHE) gamma-rays above 10-20 TeV independently reported VHE bursts for some of bright gamma-ray bursts (GRBs). If these signals are truly from GRBs, these GRBs must emit a much larger amount of energy as VHE gamma-rays than in the ordinary photon energy range of GRBs (keV-MeV). We show that such extreme phenomena can be reasonably explained by synchrotron radiation of protons accelerated to \sim 10^{20-21} eV, which has been predicted by Totani (1998a). Protons seem to carry about (m_p/m_e) times larger energy than electrons, and hence the tot…
The DArk Matter Particle Explorer (DAMPE) experiment has recently announced the first results for the measurement of total electron plus positron fluxes between 25 GeV and 4.6 TeV. A spectral break at about 0.9 TeV and a tentative peak excess around 1.4 TeV have been found. However, it is very difficult to reproduce both the peak signal and the smooth background including spectral break simultaneously. We point out that the numbers of events in the two energy ranges (bins) close to the 1.4 TeV excess have $1σ$ deficits. With the basic physics principles such as simplicity and naturalness, we c…
We perform a detailed study of scalar dark matter with triplet Higgs extensions of the Standard Model in order to explain the cosmic ray electron and positron excesses reported by AMS-02 and DAMPE. A detailed analysis of AMS-02 positron excess reveals that for different orderings (normal, inverted and quasi-degenerate) of neutrino mass, the hybrid triplet Higgs portal framework is more favored with respect to the single triplet Higgs portal for TeV scale dark matter. We also show that the resonant peak and continuous excess in DAMPE cosmic ray data can be well explained with the hybrid triplet…
Gamma Ray Bursts (GRBs) have been proposed as one {\it possible} class of sources of the Ultrahigh Energy Cosmic Ray (UHECR) events observed up to energies $\gsim10^{20}\ev$. The synchrotron radiation of the highest energy protons accelerated within the GRB source should produce gamma rays up to TeV energies. Here we briefly discuss the implications on the energetics of the GRB from the point of view of the detectability of the prompt TeV gamma rays of proton-synchrotron origin in GRBs in the up-coming ICECUBE muon detector in the south pole.
A TeV spectral break in the total flux of cosmic-ray electrons and positrons (CREs) at which the spectral power index softens from $\sim 3$ to $\sim 4$ has been observed by H.E.S.S. and recently confirmed by DAMPE with a high significance of $6.6~σ$. Such an observation is apparently inconsistent with the data from other experiments such as Fermi-LAT, AMS-02 and CALET. We perform a global analysis to the latest CRE data including Fermi-LAT, AMS-02, CALET, DAMPE and H.E.S.S. with energy scale uncertainties taken into account to improve the consistency between the data sets. The fit result stron…
We propose that TeV $γ$-ray emission from blazars is produced by collisions near the line of sight of high energy jet protons with gas targets (``clouds'') from the broad emission-line region (BLR). Intense TeV $γ$-ray flares (GRFs) are produced when BLR clouds cross the line of sight close to the black hole. The model reproduces the observed properties of the recently reported very short and intense TeV GRFs from the blazar Markarian 421. Hadronic production of TeV GRF from blazars implies that it is accompanied by a simultaneous emission of high energy neutrinos, and of electrons and positro…
Gluons dominate the proton behavior at high energy collisions, they can be condensed at ultra high energy. The collisions of the accelerated high energy protons with interplanetary matter in cosmic rays will produce a huge number of secondary particles at the gluon condensate energy region, which break the primary power-law of cosmic rays. The above predictions seem to be consistent with the recent DAMPE data concerning the electron plus positron spectra. We find that the smoothly broken power-law at $\sim 0.9 TeV$ and $3\sim 4 TeV$ in the DAMPE data can be understood as the gluon condensation…
PAMELA's observation that the cosmic ray positron fraction increases rapidly with energy implies the presence of primary sources of energetic electron-positron pairs. Of particular interest is the possibility that dark matter annihilations in the halo of the Milky Way provide this anomalous flux of antimatter. The recent measurement of the cosmic ray electron spectrum by the Fermi Gamma Ray Space Telescope, however, can be used to constrain the nature of any such dark matter particle. In particular, it has been argued that in order to accommodate the observations of Fermi and provide the PAMEL…
The construction of the ILC tangential to Tevatron ring will give opportunity to investigate electron-proton, positron-proton, electron-antiproton, positron-antiproton interactions at 1 TeV center of mass energy. The analysis of the lepton-hadron collisions in these energy region is very important both for understanding of strong interaction dynamics and for adequate interpretation of future LHC and VLHC data. In addition, ILC-Tevatron collider will provide a possibility to realize photon-hadron collisions in the same energy region using Compton backscattered laser photon off ILC electron beam…
On the basis of existing observations (at the 4.5 σlevel) of TeV gamma-ray outbursts from the Fanaroff-Riley I (FRI) radio galaxy Centaurus A, we estimate the accompanying neutrino flux in a scenario where both photons and neutrinos emerge from pion decay. We find a neutrino flux on Earth dF_ν/dE_ν= 4.5\times 10^{-11} (E_ν/TeV)^{-2} TeV^{-1} cm^{-2} s^{-1}, equally spread in flavor as a result of maximal mixing. Such a flux will trigger at the IceCube facility about 10 showers/burst, with negligible background from atmospheric muons, and primary neutrino energies in excess of 100 TeV. The only…
There are three astroparticle physics puzzles which fire the imagination: the origin of the ``Great Positron Producer'' in the galactic bulge, the nature of the gamma-ray bursts central engine and the mechanism of supernova explosions. We show that the mirror matter model has the potential to solve all three of these puzzles in one beautifully simple strike.
We study high-energy neutrino production in collimated jets inside progenitors of gamma-ray bursts (GRBs) and supernovae, considering both collimation and internal shocks. We obtain simple, useful constraints, using the often overlooked point that shock acceleration of particles is ineffective at radiation-mediated shocks. Classical GRBs may be too powerful to produce high-energy neutrinos inside stars, which is consistent with IceCube nondetections. We find that ultralong GRBs avoid such constraints and detecting the TeV signal will support giant progenitors. Predictions for low-power GRB cla…
We discuss the one-loop radiative corrections to the reaction e^+ e^- -> X^+_a X^-_b, for a,b=1,2 where X^+_{1,2} are the charginos of the minimal supersymmetric standard model. We calculate the leading one loop radiative corrections involving loops of top, stop, bottom and sbottom quarks, working in the MS-bar scheme. At LEP2 we find positive radiative corrections typically of 10% to 15% and with a maximum value of approximately 30% if the squark mass parameters are of the order of 1 TeV. If \sqrt{s}=500 GeV we find smaller corrections but they can be also negative, with extreme values of 13%…
Gamma-ray bursts (GRBs) have been considered as potential very high-energy photon emitters due to the large amount of energy released as well as the strong magnetic fields involved in their jets. However, the detection of TeV photons is not expected from bursts beyond a redshift of $z\gtrsim 0.1$ due to their attenuation with the extragalactic background light (EBL). For these reasons, the recent observation of photons with energies of 18 and 251 TeV from GRB 221009A (z=0.151) last October 9th, 2022 has challenged what we know about the TeV-emission mechanisms and the extragalactic background.…
High energy protons produced by various sources of cosmic rays, {\it e.g.} supernova remnants, pulsar wind nebulae, active galactic nuclei and gamma-ray bursts participate in $pγ$ and $pp$ interactions. Although $pp$ interactions may be the dominant mechanism in our Galaxy, it is unclear how important $pγ$ process is. We show that the upper bound on the fraction of protons participating in $pγ$ interactions inside all Galactic astrophysical sources of cosmic rays is 10%.
The preliminary detections of the gamma-ray burst 221009A up to 18 TeV by LHAASO and up to 251 TeV by Carpet 2 have been reported through Astronomer's Telegrams and Gamma-ray Coordination Network circulars. Since this burst is at redshift $z=0.1505$, these photons may at first seem to have a low probability to avoid pair production off of background radiation fields and survive to reach detectors on Earth. By extrapolating the reported $0.1-1.0$\ GeV LAT spectrum from this burst to higher energies and using this to limit the intrinsic spectrum of the burst, we show that the survival of the 18 …
The violation of CP symmetry at the electro-weak scale is one of the essential ingredients for electro-weak baryogenesis. It is therefore of great interest to map the CP properties of the Higgs sector in as much detail as possible. A linear electron-positron Higgs factory collider will provide many opportunities to probe the CP nature of the Higgs sector, thanks to access to several Higgs production processes at a wide range of centre-of-mass energies. In this paper we report on two studies based on full simulation of detector response and realistic reconstruction algorithms: 1) a study of $h …
We argue that gamma-ray bursts (GRBs) may be the origin of the cosmic gamma-ray background radiation observed in GeV range. It has theoretically been discussed that protons may carry a much larger amount of energy than electrons in GRBs, and this large energy can be radiated in TeV range by synchrotron radiation of ultra-high-energy protons (\sim 10^{20} eV). The possible detection of GRBs above 10 TeV suggested by the Tibet and HEGRA groups also supports this idea. If this is the case, most of TeV gamma-rays from GRBs are absorbed in intergalactic fields and eventually form GeV gamma-ray back…
We investigate the indirect signatures of the Higgs portal $U(1)_X$ vector dark matter (VDM) $X_μ$ from both its pair annihilation and decay. The VDM is stable at renormalizable level by $Z_2$ symmetry, and thermalized by Higgs-portal interactions. It can also decay by some nonrenormalizable operators with very long lifetime at cosmological time scale. If dim-6 operators for VDM decays are suppressed by $10^{16}$ GeV scale, the lifetime of VDM with mass $\sim$ 2 TeV is just right for explaining the positron excess in cosmic ray recent observed by PAMELA and AMS02 Collaborations. The VDM decayi…
We show that R-parity violating decay of Wino dark matter of mass \sim 3 TeV can naturally account for the flux and spectral shape of the cosmic-ray electrons and positrons observed by the PAMELA and Fermi satellites. To provide a theoretical basis for the scenario, we also present a model that trilinear R-parity breaking appears with a coefficient suppressed by powers of the gravitino mass, which naturally leads to the Wino lifetime of O(10^26) sec.
Gamma-ray bursts (GRBs) are the most energetic explosion events in the universe. An amount of gravitational energy of the order of the rest-mass energy of the Sun is released from a small region, within seconds or longer. This should lead to the formation of a fireball of temperature in the MeV range, consisting of electrons/positrons, photons, and a small fraction of baryons. We exploit the potential of GRB fireballs for being a laboratory for testing particle physics beyond the Standard Model, where we find that Weinberg's Higgs portal model serves as a good candidate for this purpose. Due t…
In a recent letter, the AMS collaboration reported the detailed and extensive data concerning the distribution in energy of electron and positron cosmic rays. A central result of the experimental work resides in the energy regime $30\ {\rm GeV}< E < 1\ {\rm TeV}$ wherein the power law exponent of the energy distribution is measured to be $α({\rm experiment})=3.17$. In virtue of the Fermi statistics obeyed by electrons and positrons, a theoretical value was predicted as $α({\rm theory})=3.151374$ in very good agreement with experimental data. The consequences of this agreement between theory an…
Probing CP-Violating Neutral Triple Gauge Couplings at Electron-Positron Colliders
Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交大东京镭研究所）；Department of Physics, King’s College London（伦敦国王学院物理系）；Theoretical Physics Department, CERN（欧洲核子研究中心理论物理部）；School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院）；Department of Physics, Tsinghua University（清华大学物理系）；Center for High Energy Physics, Peking University（北京大学高能物理中心）；School of Physics, Peking University（北京大学物理学院）
Dominant processes of neutrino production and neutrino-induced \ep-pair production are examined in the model of a disk hyper-accreting onto a Kerr black hole. The efficiency of plasma production by a neutrino flux from the disk, obtained for the both cases of presence and absence of a magnetic field, is found to be no more than several tenths of percent and, therefore, not enough for the origin of cosmological gamma-ray bursts.
Recently, it was suggested that a photospheric component that results from the internal dissipation occurring in the optically thick inner parts of relativistic outflows may be present in the prompt $γ$/X-ray emission of gamma-ray bursts or X-ray flashes. We explore high-energy neutrino emission in this dissipative photosphere model, assuming that the composition of the outflow is baryon-dominated. We find that neutrino emission from proton-proton collision process forms an interesting signature in the neutrino spectra. Under favorable conditions for the shock dissipation site, these low-energ…
Recently cosmic ray electrons and positrons, i.e. cosmic ray charged leptons, have been observed. To understand the distances from our solar system to the sources of such lepton cosmic rays, it is important to understand energy losses from cosmic electrodynamic fields. Energy losses for ultra-relativistic electrons and/or positrons due to classical electrodynamic bremsstrahlung are computed. The energy losses considered are (i) due to Thompson scattering from fluctuating electromagnetic fields in the background cosmic thermal black body radiation and (ii) due to the synchrotron radiation losse…
We discuss the physics motivations for building a 500 - 1 TeV electron-positron linear collider. The state of the art collider technologies and the physics-driven machine parameters are discussed. A survey of some of the phenomena well suited to study at a linear collider are described, including Higgs bosons, supersymmetry, other extensions to the Standard Model, and cosmology.
The hypothesis that pulsar wind nebulae (PWNe) can significantly contribute to the excess of the positron ($e^+$) cosmic-ray flux has been consolidated after the observation of a $γ$-ray emission at TeV energies of a few degree size around Geminga and Monogem PWNe, and at GeV energies for Geminga at a much larger extension. The $γ$-ray halos around these PWNe are interpreted as due to electrons ($e^-$) and $e^+$ accelerated and escaped by their PWNe, and inverse Compton scattering low-energy photons of the interstellar radiation fields. The extension of these halos suggests that the diffusion …
We present the energy spectra of the fluxes of positrons, anti-protons and photons generated by Dark Matter annihilations in our galaxy, as univocally predicted by the model of Minimal Dark Matter. Due to multi-TeV masses and to the Sommerfeld enhancement of the annihilation cross section, distinctive signals are generated above the background, even with a modest astrophysical boost factor, in the range of energies soon to be explored by cosmic ray experiments.
We compute cosmic ray (CR) nuclei, proton, antiproton, electron and positron spectra below 1 TeV at Earth by means of a detailed transport description in the galaxy and in the solar system. CR spectra below 10 GeV are strongly modified by charge-sign dependent propagation effects. These depend on the polarity of the solar magnetic field and therefore vary with the solar cycle. The puzzling discrepancy between the low-energy positron fraction measured by PAMELA and AMS-01 is then easily explained by their different data-taking epochs. We reproduce the observed spectra of CR light nuclei within …
We treat high-energy neutrino production in GRBs. Detailed calculations of photomeson neutrino production are presented for the collapsar model, where internal nonthermal synchrotron radiation is the primary target photon field, and the supranova model, where external pulsar-wind synchrotron radiation provides important additional target photons. Detection of > 10 TeV neutrinos from GRBs with Doppler factors > 200, inferred from gamma-ray observations, would support the supranova model. Detection of < 10 TeV neutrinos is possible for neutrinos formed from nuclear production. Only the most powe…
The detectability of a possible ``high'' energy ($>100\gev$) component of Gamma-Ray Bursts (GRBs) using AMANDA/ICECUBE large area muon detectors is examined within the context of a specific model of such high energy gamma ray production within GRBs, namely, the proton-synchrotron model, which requires protons to be accelerated to ultrahigh energies $\gsim10^{20}\ev$ within GRBs. In this model, the high energy component is distinct from, but may well be emitted in coincidence with, the usual ``low'' (keV--MeV) energy component observed by satellite-borne detectors. The AMANDA/ICECUBE detectors …
