The European Physical Journal C最新文献

Correlators in monomial Hermitian matrix model strongly depend on the choice of eigenvalue integration contours. We express Schur correlator in case of several different integration contours (mixed phase case) as a sum over products of Schur correlators for just one type of contour (pure phase), where expansion coefficients are manifestly made from Littlewood–Richardson and Mugnaghan–Nakayama coefficients. Further, for pure phase Schur correlators we find concise superintegrability formulas that unify both usual and exotic cases, that before looked very different from one another.

In this work we discuss the issue of localization of (N=2) spinning particles. More specifically, we show that we can not confine the spinning particle within the Randall–Sundrum scenario. We argue that this result directly affects studies related to localization of p-form fields. We show that, due to the non confinement of the superparticle, we can not localize p-forms on the membrane.

The long-standing claim of dark matter detection by the DAMA experiment remains a crucial open question in astroparticle physics. A key step towards its independent verification is the development of NaI(Tl)-based detectors with improved sensitivity at low energies. The majority of NaI(Tl)-based experiments rely on conventional photomultiplier tubes (PMTs) as single photon detectors, which present technological limitations in terms of light collection, intrinsic radioactivity and high noise contribution at keV energies. ASTAROTH is an R&D project developing a NaI(Tl)-based detector where the scintillation light is read out by silicon photomultipliers (SiPMs) matrices. SiPMs exhibit high photon detection efficiency, negligible radioactivity, and, most importantly, a dark noise nearly two orders of magnitude lower than PMTs, when operated at cryogenic temperature. To this end, ASTAROTH features a custom-designed cryostat based on a bath of cryogenic fluid, able to safely operate the detector and the read-out electronics down to about 80 K. This work reports the first experimental characterization of an approximately 360 g NaI(Tl) detector read out by a large area (5 cm (times ) 5 cm) SiPM matrix. The net photoelectron yield obtained with a preliminary configuration is approximately 4.5 photoelectrons/keV after crosstalk correction, which is rather promising in light of several planned developments. The signal-to-noise ratio and the energy threshold attainable with SiPMs is expected to improve the sensitivity for dark matter searches beyond the reach of current-generation PMT-based detectors. This result is the first proof of the viability of this technology and sets a milestone toward the design of future large-scale experiments.

Axion-like particles (ALPs) are well-motivated extensions of the standard model (SM) that appear in numerous new physics scenarios. In this paper, we concentrate on searches for long-lived ALPs predicted by the photophobic scenario at the HL-LHC with the center-of-mass energy (sqrt{s}=14) TeV and the integrated luminosity ({mathcal {L}}=3~hbox {ab}^{-1}.) We consider the process (pp rightarrow gamma a) with the ALP a decaying into a pair of displaced charged leptons and perform a detailed analysis of two types of signals: and (.) For the signal, we find that the prospective sensitivities of the HL-LHC can reach (g_{aWW}in [8.72 times 10^{-3}, 6.42 times 10^{-2}]) (hbox {TeV}^{-1}) for the ALP mass (m_a in [4, 10]) GeV. While for the signal, the HL-LHC can probe a broader parameter space, with the sensitivities covering (m_a in [4, 10]) GeV and (g_{aWW} in [4.17 times 10^{-3}, 2.00 times 10^{-1}]) (hbox {TeV}^{-1}.) These long-lived searches complement some previous prompt decay studies from LEP and LHC experiments, extending the parameter space explored by the LHCb collaboration. Our results show that the HL-LHC has significant potential to probe long-lived ALPs via their displaced vertex signatures.

Recent research has revealed a novel nonlinear mechanism, distinct from the linear superradiant instability, which triggers the black hole bomb phenomenon. Introducing a massive complex scalar field with nonlinear self-interactions drives the Reissner–Nordström black hole to shed substantial energy, thereby triggering a black hole bomb. Radial oscillations in the scalar hair profile are observed during this process. In this paper, we further reveal that physical quantities associated with scalar hair exhibit identical oscillation patterns during the evolution of the black hole-scalar field system. Moreover, the oscillation frequency exhibits a linear dependence on the gauge coupling constant of the scalar field with other parameters fixed. Meanwhile, the horizon radius of hairy black holes and the mass within the horizon increase monotonically with the gauge coupling constant. We have also identified a critical initial charge value that distinguishes hairy solutions that trigger black hole bombs from those that do not.

An exploratory study of the exclusive production of a vector - toponium (psi _t) state by photon–hadron interactions is performed considering proton–proton and proton–nucleus collisions at the Large Hadron Collider (LHC) and Future Circular Collider (FCC) energies. The scattering amplitude is calculated using the (k_T) - factorization formalism assuming that the vector–toponium state can be described by a Gaussian light-cone wave function and considering different models for the unintegrated gluon distribution. Predictions for the rapidity distributions and total cross - sections are presented. Our results indicate that the experimental measurement of this final state will be very difficult for the expected integrated luminosities at the LHC and FCC.

Processes with (tau )-leptons in the final state are important for Standard Model measurements and searches for physics beyond the Standard Model. The ATLAS experiment at the Large Hadron Collider observes (tau )-leptons produced in proton–proton collisions only through their decay products. Data analyses involving hadronically decaying (tau )-leptons face challenges due to backgrounds from jets misidentified as (tau )-leptons that are not modelled reliably by Monte Carlo simulations. Data-driven methods such as the fake-factor method allow such misidentified backgrounds to be predicted by measuring transfer factors, known as fake factors, in data from dedicated regions. This paper describes a refined technique for determining the fake factors, the Universal Fake Factor method. It evaluates the fake factors for a signal region by using fake factors from samples enriched in different sources of jets misidentified as (tau )-leptons (light-quark, gluon, b-quark, and pile-up jets). Each fake factor is calculated as a linear combination of fake factors measured in these different enriched samples. For the full Run 2 data set, the systematic uncertainty of the calculated fake factors, evaluated using (W(mu nu )) enriched event sample, ranges from 15 to 35% depending on the (tau )-lepton’s transverse momentum and charged-particle decay multiplicity.

Measurements of (tbar{t}ell ^{+}ell ^{-}) production in the region of high dilepton invariant mass with effective field theory (EFT) interpretations are presented. They are performed using final states with three isolated leptons (electrons or muons) and are based on (sqrt{s} = 13) (text {T}text {e}hspace{-1.00006pt}text {V}) proton–proton collision data with an integrated luminosity of (140,textrm{fb}^{-1}), recorded from 2015 to 2018 with the ATLAS detector at the Large Hadron Collider. Measurements of the (tbar{t},ell ^+ell ^-) signal strength and cross-section upper-limits are performed inclusively in lepton flavour and separately for electrons and muons. The study also aims to probe anomalous four-fermion interactions including to test for possible lepton flavor universality violation. No significant deviations from the Standard Model predictions are observed and the measurements are interpreted through the EFT formalism to provide new constraints on the relevant operators.

We investigate cosmological solutions for the modified gravity theory obtained from quantum relative entropy between the metric of spacetime and the metric induced by the geometry and matter fields. The vacuum equations admit inflationary solutions, hinting at an entropic origin for inflation. Equations also admit a regime of phantom like behavior. Assuming that the relation between slow roll parameters and CMB observables holds for “gravity from entropy”, the theory predicts a viable spectrum.