The European Physical Journal C最新文献

Ordinary matter coupled to light weakly interacting bosons can lead to the formation of a macroscopic bosonic field in the vicinity of large matter concentrations such as ordinary or neutron stars. When these objects are turned into black holes due to a supernova or a binary merger this “hair” could be “shorn” off. Part of the field configuration would then be released leading to an outgoing field wave. For small masses this field transient remains rather compact and can induce a transient signal in experiments, in particular those that look for wave-like dark matter. This signal can be correlated with the corresponding astrophysical signal of the event. In this note, we consider a variety of couplings and the associated signals and estimate the corresponding sensitivities.

In this paper, we explore the Oscillating Asymmetric Dark Matter (OADM) model to address the core-cusp problem, aiming to resolve the discrepancy between the predictions of the (Lambda textrm{CDM}) cosmological model and the observed dark matter profiles in dwarf spheroidal galaxies. The reactivation of dark matter annihilation during the structure formation epoch is possible if there is a small Majorana mass term that breaks the conservation of dark matter particle number, leading to oscillations between dark matter and its antiparticle. We analyzed the effects of the annihilation mechanism in the galaxy rotation curves of the SPARC and LITTLE THINGS catalogs. We searched for the characteristics of the OADM model which best describes the data. Our results show that the OADM model can successfully turn originally cusp-type halos into core-type ones according to our data sample.

This study extends the concept of cracking to self-gravitating, spherically symmetric compact objects in modified (f(R, varphi )) theory of gravity, where R represents the Ricci scalar, and (varphi ) is the scalar potential. In this regard, we consider spherically symmetric spacetime characterized with an anisotropic matter to detect the instabilities of self-gravitating compact objects via cracking and overturning. Further, we construct the general framework to observe the cracking and overturning points by applying the local density perturbation technique to the configuration governed by barotropic equation of state. The effectiveness of this approach is assessed by analyzing its results on the data of Her X-1, SAX J1808.4-3658, and 4U 1820-30 respectively. It is concluded that cracking points appear in the different interior regions of these three stars. Significantly, this study illustrates the effectiveness of the cracking approach by highlighting the regions sensitive to localized density disruptions, offering valuable insights into the structural behavior of compact stars within a modified gravity framework.

We explore the possibility of using ultra-periphe- ral proton-lead collisions at the LHC to study inclusive vector-quarkonium photoproduction, that occurs when a quasi-real photon emitted by a fully stripped lead ion breaks a proton to produce a vector quarkonium. Owing to the extremely large energies of the colliding hadrons circulating in the LHC, the range of accessible photon-nucleon centre-of-mass energies, (W_{gamma p}), largely exceeds what has been and will be studied at lepton-hadron colliders, HERA and the EIC. We perform a tune to HERA photoproduction data, use this tune to predict the yields of photoproduced (J/psi ), and estimate the corresponding transverse-momentum reach at LHC experiments. We also model the hadroproduction background and demonstrate that inclusive photoproduction can be isolated at the LHC from such background by imposing constraints on the hadronic activity in the lead-going direction at mid, forward, or far-forward rapidities depending on the capability of the detector under consideration. We find that the resulting cross sections are large enough to be measured by ALICE, ATLAS, CMS, and LHCb. We estimate the background-to-signal ratio after isolation to be of the order of 0.001 and 0.1 in the low and large transverse-momentum regions, respectively. In addition, we propose and assess the Jacquet–Blondel method to reconstruct the photon-nucleon centre-of-mass energy and the fractional energy of the quarkonium with respect to the photon.

We present a method to simulate toponium formation events at the LHC using the Green’s function of non-relativistic QCD in the Coulomb gauge, which governs the momentum distribution of top quarks in the presence of the QCD potential. This Green’s function can be employed to re-weight any matrix elements relevant for (t{bar{t}}) production and decay processes where a colour-singlet top–antitop pair is produced in the S-wave at threshold. As an example, we study the formation of (eta _t) toponium states in the gluon fusion channel at the LHC, combining the re-weighted matrix elements with parton showering.

We study the impact of state-of-the-art top-quark data collected at the large hadron collider on parton distribution functions (PDFs). Following the ABMP methodology, the fit extracts simultaneously proton PDFs, the strong coupling (alpha _s(M_Z)) and heavy-quark masses at next-to-next-to-leading order (NNLO) accuracy in QCD. It includes recent high-statistics data on absolute total inclusive cross sections for   (tbar{t}+X), the sum of ((t + X)) and ((bar{t} + X)) hadroproduction, and normalized inclusive data double-differential in the invariant mass and rapidity of the (tbar{t}) pair at (sqrt{S}=13) TeV. The gluon PDF at large x and the top-quark mass value derived from these data are well compatible with the previous ABMP16 results, but with significantly smaller uncertainties, reduced by up to a factor of two. At NNLO in QCD we obtain for the strong coupling the value (alpha _s^{(n_f=5)}(M_Z)= 0.1150 pm 0.0009) and for the top-quark mass in the ({overline{text{ MS }}})-scheme (m_t(m_t) = 160.6 pm 0.6) GeV, corresponding to (m_t^textrm{pole} = 170.2 pm 0.7) GeV in the on-shell scheme. The new fit, dubbed ABMPtt, is publicly released in grids in LHAPDF format.

The Gamma Variance Model is a statistical model that incorporates uncertainties in the assignment of systematic errors (informally called errors-on-errors). The model is of particular use in analyses that combine the results of several measurements. In the past, combinations have been carried out using two alternative approaches: the Best Linear Unbiased Estimator (BLUE) method or what we will call the nuisance-parameter method. In this paper, we obtain a general relation between the BLUE and nuisance-parameter methods when the correlations induced by systematic uncertainties are non-trivial (i.e., not (pm 1) or 0), and we then generalise the nuisance-parameter approach to include errors-on-errors. We then present analytical formulas for estimating central values, confidence intervals, and goodness-of-fit when errors-on-errors are incorporated into the statistical model. To illustrate the properties of the Gamma Variance Model, we apply it to the 7–8 TeV ATLAS–CMS top quark mass combination. We also explore a hypothetical scenario by artificially adding a fictitious measurement as an outlier to the combination, illustrating a key feature of the Gamma Variance Model – its sensitivity to the internal consistency of the input data – which could become relevant for future combinations.

We study supersymmetric (AdS_6) black holes from matter-coupled F(4) gauged supergravity coupled to four vector multiplets with (ISO(3)times U(1)) gauge group. This gauged supergravity admits a maximally supersymmetric (AdS_6) vacuum with (SO(3)subset ISO(3)) symmetry. We find a number of new supersymmetric (AdS_2times mathcal {M}_4) solutions by performing topological twists along (mathcal {M}_4). For (mathcal {M}_4) being a product of two Riemann surfaces (Sigma times widetilde{Sigma }), we perform a twist by (SO(2)times U(1)) gauge fields and find (AdS_2times Sigma times widetilde{Sigma }) solutions for at least one of the Riemann surface being negatively curved. For (mathcal {M}_4) being a Kahler four-cycle (mathcal {M}_{text {K}4}), a twist by (SO(2)times U(1)) gauge fields leads to (AdS_2times mathcal {M}_{text {K}4}^-) solutions for negatively curved (mathcal {M}_{text {K}4}). Finally, performing a twist by turning on SO(3) gauge fields in the case of (mathcal {M}_4) being a Cayley four-cycle (mathcal {M}_{text {C}4}) also leads to (AdS_2times mathcal {M}_{text {C}4}^-) solutions for negatively curved (mathcal {M}_{text {C}4}). We give numerical black hole solutions interpolating between all of these (AdS_2times mathcal {M}_4) near horizon geometries and the asymptotically locally (AdS_6) vacuum. It is also possible to uplift all of these solutions to type IIB theory via consistent truncations on (S^2times Sigma ) leading to a new class of supersymmetric (AdS_2times mathcal {M}_4times S^2times Sigma ) solutions.

A search for a light charged Higgs boson produced in decays of the top quark, (t rightarrow H^{pm } b) with (H^{pm } rightarrow cs), is presented. This search targets the production of top-quark pairs (tbar{t} rightarrow Wb H^{pm } b), with (W rightarrow ell nu ) ((ell = e, mu )), resulting in a lepton-plus-jets final state characterised by an isolated electron or muon and at least four jets. The search exploits b-quark and c-quark identification techniques as well as multivariate methods to suppress the dominant (tbar{t}) background. The data analysed correspond to (140hbox { fb}^{-1}) of (pp) collisions at (sqrt{s} = 13hbox { TeV}) recorded with the ATLAS detector at the LHC between 2015 and 2018. Observed (expected) 95% confidence-level upper limits on the branching fraction (mathscr {B}(trightarrow H^{pm } b)), assuming (mathscr {B}(trightarrow Wb) + mathscr {B}(t rightarrow H^{pm } (rightarrow cs)b)=1.0), are set between 0.066% (0.077%) and 3.6% (2.3%) for a charged Higgs boson with a mass between 60 and 168 GeV.

We study the low-energy effective theories of photons and gravitons, matching them at one loop to a UV completion with a massive spinning matter particle. The matter is allowed to have non-minimal electromagnetic and gravitational interactions. We construct the one-loop 4-photon and 4-graviton helicity amplitudes with matter in the loop carrying anomalous multipole moments, and we read off the Wilson coefficients in the effective theory below the matter particle mass. Much as in the case of minimal coupling, the Wilson coefficients beyond the leading order turn out to be confined to small islands in the much larger theory space allowed by existing positivity constraints.