Light-by-light scattering is a relatively new area in experimental physics. Since its first observation in 2017 by the ATLAS collaboration, which was reported in Nature [1], only three studies have been published with new results [2-4], all within a similar kinematic range. Our recent research [5] shows that studying two-photon measurements in regions with lower transverse momentum...
This extension has a new vector massive boson (Chern-Simons boson) that couples to electroweak gauge bosons by the so-called effective Chern-Simons interaction. There is no direct interaction between the Chern-Simons bosons and SM fermions. We consider the effective loop interaction of a new vector boson with SM fermions and consider the possibility of the manifestation of the GeV-scale...
New physics models allow Lepton Flavor Violating (LFV) reactions which are exactly forbidden in the standard model. Hence search for LFV is a clue to the new physics, which unveil the flavor structure and the symmetries behind it. We revisit LFV lepton-nucleus deep inelastic scattering, $\ell_i N \to \ell_j X$ ($\ell_i$ and $\ell_j$ are different flavor lepton, N is nucleus, and X is hadron),...
The cosmic microwave background (CMB) has been measured with the COBE, WMAP and Planck space missions. Its black-body Planckian spectrum as determined by COBE-FIRAS corresponds to a mean temperature of $T_\text{CMB}$ = (2.725 ± 0.001) K, and Planck accurately mapped the spatial temperature fluctuations at the level of $∆T/T ≃ 6 × 10^{−6}$, thus allowing for conclusions about structure...
The Earth’s atmosphere is constantly bombarded by charged particles with energies ranging from a few GeV to several hundred EeV. In the latter range, the flux of these so-called ultra-high-energy cosmic rays rapidly decreases, making their observation reliant on large ground experiments that detect their interactions with the atmosphere and the subsequent extensive air showers they produce....
The Pierre Auger Observatory, the world’s largest observatory of ultra-high-energy cosmic rays (UHECR), offers a unique insight into the properties of hadronic interactions occurring in air showers at energies well above those reached at human-made accelerators. The key probe into the hadronic interactions has, for a long time, been the number of muons arriving at the ground, which can be...
Data from multiple experiments suggest that the current interaction models used in Monte Carlo simulations do not correctly reproduce the hadronic interactions in air showers produced by ultra-high-energy cosmic rays (UHECR), in particular – but not limited to – the production of muons during the showers. We have created a large library of UHECR simulations where the interactions at the...
The Pierre Auger Observatory is the world's largest facility for detecting ultrahigh-energy cosmic rays that has been operating for nearly 20 years. The hybrid concept of the detector allows accurate estimations of the energy spectrum, mass composition, and arrival directions of cosmic rays, which are crucial for identifying the origin and nature of the highest energy particles arriving at...
We study capability of the ILC beam dump experiment to search for new
physics, comparing the performance of the electron and positron beam
dumps.
Firstly, the dark photon, axion-like particles, and light scalar
bosons are considered as new physics scenarios. We find that the ILC
beam dump experiment has higher sensitivity than past beam dump
experiments, with the positron beam dump...
A key focus of the physics program at the LHC is the study of head-on proton-proton collisions. However, an important class of physics can be studied for cases where the protons narrowly miss one another and remain intact. In such cases, the electromagnetic fields surrounding the protons can interact producing high-energy photon-photon collisions. Alternatively, interactions mediated by the...
The study of flow harmonics provides valuable insights into the dynamics and properties of the Quark-Gluon Plasma (QGP) medium produced in heavy-ion collisions. The directed flow ($v_{1}$) slope ($dv_{1}/dy$) of protons at mid-rapidity is expected to be sensitive to the first-order phase transition. The number of constituent quark (NCQ) scaling of elliptic flow ($v_{2}$) can be regarded as a...
The unique capability of the Relativistic Heavy Ion Collider (RHIC) to collide polarized protons provides an ideal testing ground for exploring a wide range of topics in spin physics. This, along with the excellent coverage and particle identification provided by the STAR detector, has opened new avenues for investigating the proton spin structure.
This overview talk will encompass recent...
The Compressed Baryonic Matter (CBM) experiment is currently under construction at the Facility for Antiproton and Ion Research (FAIR). Its goal is to explore the phase structure of strongly interacting (QCD) matter at high net-baryon densities and moderate temperatures through heavy-ion and hadron collisions in the energy range of \sqrt{s_{NN}} = 2.9 - 4.9 GeV using the SIS100 beams. As a...
Heavy-ion collisions at relativistic energies offer an unique opportunity to investigate the properties of highly excited dense nuclear matter in the laboratory. The transverse momentum distributions of identified hadrons contain information about the collective expansion of the nuclear matter created in these collisions. In this work, a study of the average transverse momentum <pT> of bulk...
Direct photons, as electromagnetic probes that do not interact strongly with the medium, provide a unique insight into the properties of quark-gluon plasma formed in high-energy heavy-ion collisions. The PHENIX experiment at RHIC has performed a detailed analysis of the direct-photon spectrum from Au+Au collisions at √sNN = 200 GeV, utilizing the external-photon-conversion technique for a...
The STAR (Solenoidal Tracker at RHIC) experiment is conducted at the
Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory.
Originally designed to study the properties of the Quark-Gluon Plasma (QGP) and the nature of strongly interacting matter under extreme conditions similar to those in the early Universe, STAR’s scope expanded with the initiation of the Beam Energy...
Heavy neutral leptons (HNLs) leave behind effective interactions of Standard Model particles, leading in particular to charged lepton flavor violation (cLFV) processes. Non observation of cLFV processes puts therefore constraints on the parameters of the HNLs. We find the relations between the effective operators in the realistic case when neutrino masses are non-zero and the HNLs are...
NA61/SHINE is a fixed-target experiment at the CERN SPS. Its spectrometer has unique properties including large particle acceptance and precise momentum measurement. These properties and high statistics of collected proton-proton collisions at beam momentum 158 GeV/c allow analyzing the transverse polarization of Λ hyperons produced in the primary vertex.
The opportunities for measurements...
The existence and location of the QCD critical point are objects of both experimental and theoretical studies. The comprehensive data collected by NA61/SHINE during a two-dimensional scan in beam momentum and system size allows for a systematic search for the critical point - a search for a non-monotonic dependence of various correlation and fluctuation observables on collision energy and...
NA61/SHINE is a multipurpose fixed-target experiment located at CERN SPS. One of its main goals is to study the onset of deconfinement and the properties of strongly interacting matter. For this purpose, a unique two-dimensional scan in collision energy ($\sqrt{s_{NN}} = 5.1 -16.8/17.3$ GeV) and system size was performed.
Results on identified hadron spectra produced in nucleus-nucleus...
NA61/SHINE is a multipurpose, fixed-target experiment located at the CERN Super Proton Synchrotron that has been designed to investigate the phase diagram of strongly interacting matter. This is achieved through a two-dimensional scan of the diagram by varying the beam momentum (13A-150(8)A GeV/c) and the system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb). The purpose of these measurements is...
The study of open charm hadron production provides an efficient tool for detailed investigation of the properties of hot and dense matter formed in relativistic nucleus-nucleus collisions. In particular, charm mesons are of vivid interest in the context of the phase transition between confined hadronic matter and the quark-gluon plasma as well as for the interpretation of data on J/ψ...
The NA62 experiment at CERN collected the world’s largest dataset of charged kaon decays in 2016-2018, leading to the first measurement of the branching ratio of the ultra-rare $K^+ \to \pi^+ \nu \bar\nu$ decay, based on 20 candidates.
In this talk NA62 reports new results from the analyses of rare kaon and pion decays, using data samples collected in 2017-2018. A sample of $K^+ \to \pi^+...
