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Relativistic periastron advance beyond Einstein theory: analytical solution with applications
No full textWe find a new solution to calculate the orbital periastron advance of a test body subject to a central gravitational force field for relativistic theories and models beyond Einstein. This analitycal formula has general validity that includes all the post-Newtonian (PN) contributions to the dynamics and is useful for high-precision gravitational tests. The solution is directly applicable to corrective potentials of various forms, without the need for numerical integration. Later, we apply it to the scalar tensor fourth order gravity (STFOG) and noncommutative geometry, providing corrections to the Newtonian potential of Yukawa-like form , and we conduct the first analysis involving all the PN terms for these theories. The same work is performed with a Schwarzschild geometry perturbed by a Quintessence Field, leading to a power-law potential . Finally, by using astrometric data of the Solar System planetary precessions and those of the S2 star around Sgr A*, we infer new theoretical constraints and improvements in the bounds for . The resulting simulated orbits turn out to be compatible with general relativity
Improved measurement of the decays <math display="inline"><msup><mi>η</mi><mo>′</mo></msup><mo stretchy="false">→</mo><msup><mi>π</mi><mo>+</mo></msup><msup><mi>π</mi><mo>-</mo></msup><msup><mi>π</mi><mrow><mo>+</mo><mo stretchy="false">(</mo><mn>0</mn><mo stretchy="false">)</mo></mrow></msup><msup><mi>π</mi><mrow><mo>-</mo><mo stretchy="false">(</mo><mn>0</mn><mo stretchy="false">)</mo></mrow></msup></math> and search for the rare decay <math display="inline"><msup><mi>η</mi><mo>′</mo></msup><mo stretchy="false">→</mo><mn>4</mn><msup><mi>π</mi><mn>0</mn></msup></math>
No full textUsing a sample of 10 billion J/ψ events collected with the BESIII detector, the decays η′→π+π-π+π-, η′→π+π-π0π0 and η′→4π0 are studied via the process J/ψ→γη′. The branching fractions of η′→π+π-π+π- and η′→π+π-π0 π0 are measured to be (8.56±0.25(stat)±0.23(syst))×10-5 and (2.12±0.12(stat)±0.10(syst))×10-4, respectively, which are consistent with previous measurements but with improved precision. No significant η′→4π0 signal is observed, and the upper limit on the branching fraction of this decay is determined to be less than 1.24×10-5 at the 90% confidence level. In addition, an amplitude analysis of η′→π+π-π+π- is performed to extract the doubly virtual isovector form factor α for the first time. The measured value of α=1.22±0.33(stat)±0.04(syst), is in agreement with the prediction of the vector meson dominance model
Euclid preparation - XL. Impact of magnification on spectroscopic galaxy clustering
No full textIn this paper we investigate the impact of lensing magnification on the analysis of Euclid's spectroscopic survey using the multipoles of the two-point correlation function for galaxy clustering. We determine the impact of lensing magnification on cosmological constraints as well as the expected shift in the best-fit parameters if magnification is ignored. We considered two cosmological analyses: (i) a full-shape analysis based on the Λ cold dark matter (CDM) model and its extension w0waCDM and (ii) a model-independent analysis that measures the growth rate of structure in each redshift bin. We adopted two complementary approaches in our forecast: the Fisher matrix formalism and the Markov chain Monte Carlo method. The fiducial values of the local count slope (or magnification bias), which regulates the amplitude of the lensing magnification, have been estimated from the Euclid Flagship simulations. We used linear perturbation theory and modelled the two-point correlation function with the public code coffe. For a ΛCDM model, we find that the estimation of cosmological parameters is biased at the level of 0.4–0.7 standard deviations, while for a w0waCDM dynamical dark energy model, lensing magnification has a somewhat smaller impact, with shifts below 0.5 standard deviations. For a model-independent analysis aimed at measuring the growth rate of structure, we find that the estimation of the growth rate is biased by up to 1.2 standard deviations in the highest redshift bin. As a result, lensing magnification cannot be neglected in the spectroscopic survey, especially if we want to determine the growth factor, one of the most promising ways to test general relativity with Euclid. We also find that, by including lensing magnification with a simple template, this shift can be almost entirely eliminated with minimal computational overhead.Key words: cosmological parameters / cosmology: theory / large-scale structure of Univers
Emergence of Long-Range Angular Correlations in Low-Multiplicity Proton-Proton Collisions
No full textThis Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s=13 TeV. Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4<|Δη|<1.8 and a transverse momentum of 1<pT<2 GeV/c, as a function of the charged-particle multiplicity measured at midrapidity. This Letter extends the measurements of the ridge yield to the low multiplicity region, where in hadronic collisions it is typically conjectured that a strongly interacting medium is unlikely to be formed. The precision of the new low multiplicity results allows for the first direct quantitative comparison with the results obtained in e+e- collisions at s=91 GeV and s=183–209 GeV, where initial-state effects such as preequilibrium dynamics and collision geometry are not expected to play a role. In the multiplicity range 8≲⟨Nch⟩≲24 where the e+e- results have good precision, the measured ridge yields in pp collisions are substantially larger than the limits set in e+e- annihilations. Consequently, the findings presented in this Letter suggest that the processes involved in e+e- annihilations do not contribute significantly to the emergence of long-range correlations in pp collisions
Observation of Enhanced Long-Range Elliptic Anisotropies Inside High-Multiplicity Jets in <math display="inline"><mi>p</mi><mi>p</mi></math> Collisions at <math display="inline"><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt><mo>=</mo><mn>13</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></mrow></math>
No full textA search for collective effects inside jets produced in proton-proton collisions is performed via correlation measurements of charged particles using the CMS detector at the CERN LHC. The analysis uses data collected at a center-of-mass energy of s=13 TeV, corresponding to an integrated luminosity of 138 fb-1. Jets are reconstructed with the anti-kT algorithm with a distance parameter of 0.8 and are required to have transverse momentum greater than 550 GeV and pseudorapidity |ηjet|<1.6. Two-particle correlations among the charged particles within the jets are studied as functions of the particles' azimuthal angle and pseudorapidity separations (Δϕ* and Δη*) in a jet coordinate basis, where particles' η*, ϕ* are defined relative to the direction of the jet. The correlation functions are studied in classes of in-jet charged-particle multiplicity up to Nchj≈100. Fourier harmonics are extracted from long-range azimuthal correlation functions to characterize azimuthal anisotropy for |Δη*|>2. For low-Nchj jets, the long-range elliptic anisotropic harmonic, v2*, is observed to decrease with Nchj. This trend is well described by Monte Carlo event generators. However, a rising trend for v2* emerges at Nchj≳80, hinting at a possible onset of collective behavior, which is not reproduced by the models tested. This observation yields new insights into the dynamics of jet evolution in the vacuum
Observation of strangeness enhancement with charmed mesons in high-multiplicity <math display="inline"><mi>p</mi><mi>Pb</mi></math> collisions at <math display="inline"><msqrt><msub><mi>s</mi><mrow><mi>NN</mi></mrow></msub></msqrt><mo>=</mo><mn>8.16</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>
No full textThe production of prompt Ds+ and D+ mesons is measured by the LHCb experiment in proton-lead (pPb) collisions in both the forward (1.5<y*<4.0) and backward (-5.0<y*<-2.5) rapidity regions at a nucleon-nucleon center-of-mass energy of sNN=8.16 TeV. The nuclear modification factors of both Ds+ and D+ mesons are determined as a function of transverse momentum, pT, and rapidity. In addition, the Ds+ to D+ cross section ratio is measured as a function of the primary charged particle multiplicity in the event. An enhanced Ds+ to D+ production in high-multiplicity events is observed for the whole measured pT range, in particular at low pT and backward rapidity, where the significance exceeds six standard deviations. This constitutes the first observation of strangeness enhancement in charm quark hadronization in high-multiplicity pPb collisions. The results are also qualitatively consistent with the presence of quark coalescence as an additional charm quark hadronization mechanism in high-multiplicity proton-lead collisions
Bayesian analysis of muon capture on the deuteron in chiral effective field theory
No full textWe compute the muon capture on deuteron in the doublet hyperfine state for a variety of nuclear interactions and consistent nuclear currents. Our analysis includes a detailed examination of the theoretical uncertainties coming from different sources: the single-nucleon axial form factor, the truncation of the interaction and current chiral expansion, and the model dependence. Moreover, we study the impact of the use of different power counting scheme for the electroweak currents on the truncation error. To estimate the truncation error of the chiral expansion of interactions and currents we use the most modern techniques based on Bayesian analysis. This method enables us to give a clear statistical interpretation of the computed theoretical uncertainties. Finally, we provide the differential capture rate as function of the kinetic energy of the outgoing neutron which may be measured in future experiments. Our recommended theoretical value for the total doublet capture rate is Γth=395±10s−1 (68% confidence level). We calculated also the capture rate in the quartet hyperfine state, which turns out to be in the range [13.3–13.8] s−1 depending on the adopted nuclear interaction
Space radiation environment activities in ASIF support center at Physics Dep. of Milano Bicocca University
Get PDF<p>The ASIF program has been established as a partnership agreement between the Italian institutions involved in space, technology, and particle accelerator research: ASI, ENEA and INFN. It aims to make available, to space communities, a coordinated set of irradiation facilities by means of the ASIF gateway website (<a href='\"http://www.asifgateway.asi.it/\"'>www.asifgateway.asi.it</a>) developed in the ASIF support center at the Physics Department of Milano-Bicocca University. Furthermore, the project allows for conducting research and technology programs targeted at expanding the knowledge of radiation damage mechanisms and developing simulation tools to model particle fluxes and their transport to predict the expected operating conditions in the space radiation environment. As an example, within the space radiation environment activities of ASIF calculators were made available for assessing the effects due to large energy deposition in devices (e.g., SEE) and cosmic rays fluences on the devices along a custom transfer orbit provided by the user, for determining the electronic stopping power and total ionizing dose (TID), NIEL and Total non-ionizing dose (TNID). More tools are available at the ASIF-supported websites: <a href='\"http://www.sr-niel.org/\"'>www.sr-niel.org</a>, <a href='\"http://www.helmod.org/\"'>www.helmod.org,</a> and <a href='\"http://www.geomagsphere.org/\"'>www.geomagsphere.org</a>. </p>
Fate of Galilean relativity in minimal-length theories
No full textA number of arguments at the interplay of general relativity and quantum theory suggest an operational limit to spatial resolution, conventionally modeled as a generalized uncertainty principle (GUP). Recently, it has been demonstrated that the dynamics postulated as a part of these models are only loosely related to the existence of the minimal-length scale. In this paper, we intend to make a more informed choice on the Hamiltonian by demanding, among other properties, that the model be invariant under (possibly) deformed Galilean transformations in one dimension. In this vein, we study a two-particle system with general interaction potential under the condition that the addition of two wave numbers as well as the action of Galilean boosts on wave numbers be nonlinearly deformed so as to comply with the cutoff. We find that the customary GUP Hamiltonian does not allow for invariance under (any kind of) generalized Galilean transformations. Those Hamiltonians which allow for a deformed relativity principle have to be related to the ordinary Galilean ones by virtue of a momentum-space diffeomorphism, i.e., a canonical transformation. Far from being trivial, the resulting dynamics is deformed, as we show at the example of the harmonic interaction
Particle production from non-minimal coupling in a symmetry breaking potential transporting vacuum energy
No full textWe propose an inflationary scenario where the inflaton field is non-minimally coupled to spacetime curvature and inflation is driven by a vacuum energy symmetry breaking potential without specifying a priori whether the inflaton field is small or large. As we incorporate vacuum energy into our analysis, we further explore the implications of a non-zero potential offset within inflationary dynamics. We propose that vacuum energy can transform into particles as a result of the transition triggered by spontaneous symmetry breaking. This entails a vacuum energy cancellation that yields an effective cosmological constant during inflation by virtue of a quasi-de Sitter evolution and shows that vacuum energy contribution can manifest as geometric particles produced by inflaton fluctuations, with particular emphasis on super-Hubble modes. We conjecture these particles as quasi-particles arising from interaction between the inflaton and spacetime geometry, enhanced by non-minimal coupling. Specifically, we propose that dark matter arises from a pure geometric quasi-particle contribution, quantifying the corresponding dark matter candidate ranges of mass. In this scenario, we further find that a zero potential offset leads to a bare cosmological constant at the end of inflation, while a negative offset would require an additional kinetic (or potential) contribution in order to be fully-canceled. In this regard, we conclude that the scenario of large-field inflation is preferred since it necessitates a more appropriate selection of the offset. Our conclusion is reinforced as small-field inflation would lead to a significant screening of the Newtonian gravitational constant as inflation ends