# The European Physical Journal C

## List of Papers (Total 3,659)

#### Probing the unitarity of the renormalizable theory of massive conformal gravity

The presence of an unstable massive spin-2 ghost state in the renormalizable theory of massive conformal gravity leads to a pair of complex poles appearing in the first sheet of the energy plane. Here we show that the positions of these poles are gauge dependent, which makes the theory unitary.

#### The $$Z_c(3900)$$ peak does not come from the “triangle singularity”

We compare contributions from the triangle diagram and the $$D\bar{D}^*$$ bubble chain with the processes of $$e^{+}e^{-}\rightarrow J/\psi \pi ^{+}\pi ^{-}$$ and $$e^{+}e^{-}\rightarrow (D\bar{D}^*)^\mp \pi ^{\pm }$$. By fitting the $$J/\psi \pi$$ maximum spectrum and the $$D\bar{D}^*$$ spectrum, we find that the triangle diagram cannot explain the new experimental results from...

#### Footprints of leptoquarks: from $$R_{K^{(*)}}$$ to $$K \rightarrow \pi \nu \bar{\nu }$$K→πνν¯

Rare $$K \rightarrow \pi \nu \bar{\nu }$$ decays, being dominated by short distance contributions within the standard model (SM), open a window for new physics (NP) searches at low energies. The $$K \rightarrow \pi \nu \bar{\nu }$$ branching ratios are expected to be measured with $$\sim 10\%$$ accuracies by NA62/CERN and KOTO/JPARC. The theoretical uncertainties of branching...

#### Logarithmic correction to BMSFT entanglement entropy

Using Rindler method we derive the logarithmic correction to the entanglement entropy of a two dimensional BMS-invariant field theory (BMSFT). In particular, we present a general formula for extraction of the logarithmic corrections to both the thermal and the entanglement entropies. We also present a CFT formula related to the logarithmic correction of the BTZ inner horizon...

#### A multi-isotope $$0\nu 2\beta$$ bolometric experiment

There are valuable arguments to perform neutrinoless double beta ($$0\nu 2\beta$$) decay experiments with several nuclei: the uncertainty of nuclear-matrix-element calculations; the possibility to test these calculations by using the ratio of the measured lifetimes; the unpredictability of possible breakthroughs in the detection technique; the difficulty to foresee background in...

#### Statistical analysis with cosmic-expansion-rate measurements and two-point diagnostics

Direct measurements of Hubble parameters H(z) are very useful for cosmological model parameters inference. Based on them, Sahni, Shafieloo and Starobinski introduced a two-point diagnostic $$Omh^2(z_i, z_j)$$ as an interesting tool for testing the validity of the $$\Lambda \hbox {CDM}$$ model. Applying this test they found a tension between observations and predictions of the...

#### Leptonic flavor structure in the brane shifted extra dimensional seesaw mechanism

We discuss the leptonic flavor structure generated by a brane shifted extra dimensional seesaw model with a single right handed neutrino in the bulk. In contrast to previous works, no unitarity approximation for the $$3 \times 3$$ submatrix has been employed. This allows to study phenomenological signatures such as lepton flavor violating decays. A strong prediction of the model...

#### General expressions for extra-dimensional tree amplitudes and all-plus 1-loop integrands in $$\mathcal {}$$-cut representation

In this paper, we give the general expressions for a special series of tree amplitudes of the Yang–Mills theory. This series of amplitudes have two adjacent massless spin-1 particles with extra-dimensional momenta and any number of positive helicity gluons. With special helicity choices, we use the spinor helicity formalism to express these n-point amplitudes in compact forms...

#### From identical S- and P-wave $$p_\mathrm{T}$$ spectra to maximally distinct polarizations: probing NRQCD with $$\chi$$χ states

A global analysis of ATLAS and CMS measurements reveals that, at mid-rapidity, the directly-produced $$\chi _{c1}$$, $$\chi _{c2}$$ and J/$$\psi$$ mesons have differential cross sections of seemingly identical shapes, when presented as a function of the mass-rescaled transverse momentum, $$p_\mathrm{T}/M$$. This identity of kinematic behaviours among S- and P-wave quarkonia is...

#### Closing in on the radiative weak chiral couplings

We point out that, given the current experimental status of radiative kaon decays, a subclass of the $$\mathcal{O} (p^4)$$ counterterms of the weak chiral lagrangian can be determined in closed form. This involves in a decisive way the decay $$K^\pm \rightarrow \pi ^\pm \pi ^0 l^+ l^-$$, currently being measured at CERN by the NA48/2 and NA62 collaborations. We show that...

#### Generalizing the $$\mathfrak {bms}_{3}$$ and 2D-conformal algebras by expanding the Virasoro algebra

By means of the Lie algebra expansion method, the centrally extended conformal algebra in two dimensions and the $$\mathfrak {bms}_{3}$$ algebra are obtained from the Virasoro algebra. We extend this result to construct new families of expanded Virasoro algebras that turn out to be infinite-dimensional lifts of the so-called $$\mathfrak {B}_{k}$$, $$\mathfrak {C}_{k}$$ and...

#### Constraints on low energy QCD parameters from $$\eta \rightarrow 3\pi$$ and $$\pi \pi$$ππ scattering

The $$\eta \,\rightarrow \,3\pi$$ decays are a valuable source of information on low energy QCD. Yet they were not used for an extraction of the three flavor chiral symmetry breaking order parameters until now. We use a Bayesian approach in the framework of resummed chiral perturbation theory to obtain constraints on the quark condensate and pseudoscalar decay constant in the...

#### Width of a two-body coupled-channel resonance

We study the width of a two-body resonance in a coupled-channel system. We demonstrate how the width does not come only determined by the available phase space for its decay to the detection channel, but it greatly depends on the relative position of the mass of the resonance with respect to the masses of the coupled-channels generating the state. Our results are consistent with...