The European Physical Journal C

http://link.springer.com/journal/10052

List of Papers (Total 3,650)

Anomaly-free models for flavour anomalies

We explore the constraints imposed by the cancellation of triangle anomalies on models in which the flavour anomalies reported by LHCb and other experiments are due to an extra U(1)\(^\prime \) gauge boson Z\(^\prime \). We assume universal and rational U(1)\(^\prime \) charges for the first two generations of left-handed quarks and of right-handed up-type quarks but allow...

A precise determination of the top-quark pole mass

The Principle of Maximum Conformality (PMC) provides a systematic way to eliminate the renormalization scheme and renormalization scale uncertainties for high-energy processes. We have observed that by applying PMC scale setting, one obtains comprehensive and self-consistent pQCD predictions for the top-quark pair total cross section and the top-quark pair forward–backward...

Regge trajectories for heavy quarkonia from the quadratic form of the spinless Salpeter-type equation

In this paper, we present one new form of the Regge trajectories for heavy quarkonia which is obtained from the quadratic form of the spinless Salpeter-type equation (QSSE) by employing the Bohr-Sommerfeld quantization approach. The obtained Regge trajectories take the parameterized form \(M^2={\beta }({c_l}l+{\pi }n_r+c_0)^{2/3}+c_1\), which are different from the present Regge...

The NNLO QCD soft function for 1-jettiness

We calculate the soft function for the global event variable 1-jettiness at next-to-next-to-leading order (NNLO) in QCD. We focus specifically on the non-Abelian contribution, which, unlike the Abelian part, is not determined by the next-to-leading order result. The calculation uses the known general forms for the emission of one and two soft partons and is performed using a...

Bouncing universe of entropy-corrected Friedmann equations

In this paper, we investigate the possibility of obtaining bouncing-oscillating solution in modified Friedmann equations with logarithmic entropy corrected, \(S=\frac{A}{4G}+\alpha \ln \frac{A}{4G}+\beta \frac{4G}{A}\), for positive, negative and zero values of \( (\alpha ,\beta )\) pre-factors and all kinds of curved universes. The results are argued using the dynamical system...

Model independent new physics analysis in $$\Lambda _b\rightarrow \Lambda \mu ^+\mu ^-$$ decay

We study the rare \(\Lambda _b\rightarrow \Lambda \mu ^+\mu ^-\) decay in the Standard Model and beyond. Beyond the Standard Model we include new vector and axial-vector operators, scalar and pseudo-scalar operators, and tensor operators in the effective Hamiltonian. Working in the helicity basis and using appropriate parametrization of the \(\Lambda _b \rightarrow \Lambda...

Universal dual amplitudes and asymptotic expansions for $$gg\rightarrow H$$ and $$H\rightarrow \gamma \gamma $$H→γγ in four dimensions

Though the one-loop amplitudes of the Higgs boson to massless gauge bosons are finite because there is no direct interaction at tree level in the Standard Model, a well-defined regularization scheme is still required for their correct evaluation. We reanalyze these amplitudes in the framework of the four-dimensional unsubtraction and the loop-tree duality (FDU/LTD), and show how...

Examining the time dependence of DAMA’s modulation amplitude

If dark matter is composed of weakly interacting particles, Earth’s orbital motion may induce a small annual variation in the rate at which these particles interact in a terrestrial detector. The DAMA collaboration has identified at a \(9.3\sigma \) confidence level such an annual modulation in their event rate over two detector iterations, DAMA/NaI and DAMA/LIBRA, each with...

Status of quarkonia-like negative and positive parity states in a relativistic confinement scheme

Properties of quarkonia-like states in the charm and bottom sector have been studied in the frame work of relativistic Dirac formalism with a linear confinement potential. We have computed the mass spectroscopy and decay properties (vector decay constant and leptonic decay width) of several quarkonia-like states. The present study is also intended to identify some of the...

Fragmentation-fra ction ratio $$f_{\Xi _ b}/f_{\Lam bda _ b}$$fΞ b/fΛ b in b- and c- baryon de cays

We study the ratio of fragmentation fractions, \(f_{\Xi _b}/f_{\Lambda _b}\), from the measurement of \(\Xi _b^0\rightarrow \Xi _c^+\pi ^-\) and \(\Lambda _b^0\rightarrow \Lambda _c^+\pi ^-\) with \(\Xi _{c}^{+}/\Lambda _{c}^{+}\rightarrow p K^-\pi ^+\). With the branching fraction \(\mathcal {B}(\Xi _c^+\rightarrow pK^-\pi ^+)=(2.2\pm 0.8)\%\) obtained under the U-spin symmetry...

Some dipole shower studies

Parton showers have become a standard component in the description of high-energy collisions. Nowadays most final-state ones are of the dipole character, wherein a pair of partons branches into three, with energy and momentum preserved inside this subsystem. For initial-state showers a dipole picture is also possible and commonly used, but the older global-recoil strategy remains...

Non-perturbative electroweak-scalegenesis on the test bench of dark matter detection

We revisit a recently proposed scale invariant extension of the standard model, in which the scalar bi-linear condensate in a strongly interacting hidden sector dynamically breaks scale symmetry, thereby triggering electroweak symmetry breaking. Relaxing the previously made assumption on \(U(N_f)\) flavor symmetry we find that the presence of the would-be dark matter candidate...

Study of the $$K_1(1270)-K_1(1400)$$ mixing in the decays $$B\rightarrow J/\Psi K_1(1270), J/\Psi K_1(1400)$$B→J/ΨK1(1270),J/ΨK1(1400)

We study the B meson decays \(B\rightarrow J/\Psi K_1(1270,1400)\) in the pQCD approach beyond the leading order. With the vertex corrections and the NLO Wilson coefficients included, the branching ratios of the considered decays are predicted as \(Br(B^+\rightarrow J/\Psi K_1(1270)^+)=1.76^{+0.65}_{-0.69}\times 10^{-3}, Br(B^+\rightarrow J/\Psi K_1(1400)^+)=6.47^{+2.50}_{-2.34...

Two-loop top and bottom Yukawa corrections to the Higgs-boson masses in the complex MSSM

Results for the two-loop corrections to the Higgs-boson masses of the MSSM with complex parameters of \({\mathcal {O}}{\left( \alpha _t^2+\alpha _t\alpha _b+\alpha _b^2\right) }\) from the Yukawa sector in the gauge-less limit are presented. The corresponding self-energies and their renormalization have been obtained in the Feynman-diagrammatic approach. The impact of the new...

Once more on Coulomb-nuclear interference

This is a critical reconsideration of the standard way of account for Coulomb-nuclear interference in the elastic scattering amplitude.

Torsion axial vector and Yvon-Takabayashi angle: zitterbewegung, chirality and all that

We consider propagating torsion as a completion of gravitation in order to describe the dynamics of curved-twisted space-times filled with Dirac spinorial fields; we discuss interesting relationships of the torsion axial vector and the curvature tensor with the Yvon-Takabayashi angle and the module of the spinor field, that is the two degrees of freedom of the spinor field itself...

Realistic simplified gaugino-higgsino models in the MSSM

We present simplified MSSM models for light neutralinos and charginos with realistic mass spectra and realistic gaugino-higgsino mixing, that can be used in experimental searches at the LHC. The formerly used naive approach of defining mass spectra and mixing matrix elements manually and independently of each other does not yield genuine MSSM benchmarks. We suggest the use of...

Hidden role of Maxwell superalgebras in the free differential algebras of D = 4 and D = 11 supergravity

The purpose of this paper is to show that the so-called Maxwell superalgebra in four dimensions, which naturally involves the presence of a nilpotent fermionic generator, can be interpreted as a hidden superalgebra underlying \(\mathcal {N}=1, {\hbox {D}}=4\) supergravity extended to include a 2-form gauge potential associated to a 2-index antisymmetric tensor. In this scenario...

On the coverage of the pMSSM by simplified model results

We investigate to which extent the SUSY search results published by ATLAS and CMS in the context of simplified models actually cover the more realistic scenarios of a full model. Concretely, we work within the phenomenological MSSM (pMSSM) with 19 free parameters and compare the constraints obtained from SModelS v1.1.1 with those from the ATLAS pMSSM study in arXiv:1508.06608. We...

Disclosing $$D^*\bar{D}^*$$ molecular states in the $$B_c^- \rightarrow \pi ^- J/\psi \omega $$Bc-→π-J/ψω decay

We study the \(B_c^- \rightarrow \pi ^- J/\psi \omega \) and \(B_c^- \rightarrow \pi ^- D^* \bar{D}^*\) reactions and show that they are related by the presence of two resonances, the X(3940) and X(3930), that are of molecular nature and couple most strongly to \(D^* \bar{D}^*\), but also to \(J/\psi \omega \). Because of that, in the \(J/\psi \omega \) mass distribution we find...

Radiative seesaw model and DAMPE excess from leptophilic gauge symmetry

In the light of the \(e^{+}+e^{-}\) excess observed by DAMPE experiment, we propose an anomaly-free radiative seesaw model with an alternative leptophilic \(U(1)_X\) gauge symmetry. In the model, only right-handed leptons are charged under \(U(1)_X\) symmetry. The tiny Dirac neutrino masses are generated at one-loop level and charged leptons acquire masses though the type-I...

keV-Scale sterile neutrino sensitivity estimation with time-of-flight spectroscopy in KATRIN using self-consistent approximate Monte Carlo

We investigate the sensitivity of the Karlsruhe Tritium Neutrino Experiment (KATRIN) to keV-scale sterile neutrinos, which are promising dark matter candidates. Since the active-sterile mixing would lead to a second component in the tritium \(\upbeta \)-spectrum with a weak relative intensity of order \(\sin ^2\theta \lesssim 10^{-6}\), additional experimental strategies are...

Running bumps from stealth bosons

For the ‘stealth bosons’ S, light boosted particles with a decay \(S \rightarrow A A \rightarrow q \bar{q} q \bar{q}\) into four quarks and reconstructed as a single fat jet, the groomed jet mass has a strong correlation with groomed jet substructure variables. Consequently, the jet mass distribution is strongly affected by the jet substructure selection cuts when applied on the...

Singlet structure function $$F_1$$ in double-logarithmic approximation

The conventional ways to calculate the perturbative component of the DIS singlet structure function \(F_1\) involve approaches based on BFKL which account for the single-logarithmic contributions accompanying the Born factor 1 / x. In contrast, we account for the double-logarithmic (DL) contributions unrelated to 1 / x and because of that they were disregarded as negligibly small...

Three waves for quantum gravity

Using effective field theoretical methods, we show that besides the already observed gravitational waves, quantum gravity predicts two further massive classical fields leading to two new massive waves. We set a limit on the masses of these new modes using data from the Eöt-Wash experiment. We point out that the existence of these new states is a model independent prediction of...