Fri·Sep 7, 2018Friday·September 7, 2018

1. 01*

   Modified Axion Electrodynamics as Impressed Electromagnetic Sources Through Oscillating Background Polarization and Magnetization

   Michael Edmund Tobar🇦🇺 · Ben T. McAllister🇦🇺 · Maxim Goryachev🇦🇺

   We present a reformulation of axion modified electrodynamics with all modifications redefined within the constitutive relations between the D,H,B and E fields. This allows the interpretation of the axion induced background bound charge, polarization current and background polarization and magnetization satisfying the charge-current continuity equation. This representation is of similar form to photon sector odd-parity Lorentz invariance violating background fields. We show that when a DC B-field is applied an oscillating background polarization is induced at a frequency equivalent to the axion mass. In contrast, when DC E-field is applied, an oscillating background magnetization is induced at a frequency equivalent to the axion mass. We show that these terms are equivalent to impressed source terms, analogous to the way that voltage and current sources are impressed into Maxwell's equations in circuit and antenna theory. The impressed source terms represent the conversion of external energy into electromagnetic energy, and in the case of axion modified electrodynamics this is due to the inverse Primakoff effect converting energy from axions into photons. The axion induced oscillating polarization under a DC magnetic field is analogous to a permanent polarised electret oscillating at the axion Compton frequency, which sources an electromotive force from an effective impressed magnetic current source. In particular, it is shown that the impressed electrical DC current that drives the solenoidal magnetic DC field of an electromagnet, induces an impressed magnetic current parallel to the DC electrical current, oscillating at the Compton frequency of the axion. We show that the magnetic current drives a voltage source through an electric vector potential and also defines the boundary condition of the oscillating axion induced polarization inside and outside the electromagnet.

   hep-phastro-ph.GAgr-qcphysics.ins-detPhys.Dark Univ.(2019)·62 citations
2. 02*

   Potential for probing three-body decays of Long-Lived Particles with MATHUSLA

   Alejandro Ibarra🇩🇪 · Emiliano Molinaro🇩🇰 · Stefan Vogl🇩🇪

   Several extensions of the Standard Model predict the existence of Long-Lived Neutral Particles (LLNPs) with masses in the multi-GeV range and decay lengths of O(100 m) or longer. These particles could be copiously produced at the LHC, but the decay products cannot be detected with the ATLAS or CMS detectors. MATHUSLA is a proposed large-volume surface detector installed near ATLAS or CMS aimed to probe scenarios with LLNPs which offers good prospects for disentangling the physics underlying two-body decays into visible particles. In this work we focus on LLNP decays into three particles with one of them being invisible, which are relevant for scenarios with low scale supersymmetry breaking, feebly interacting dark matter or sterile neutrinos, among others. We analyze the MATHUSLA prospects to discriminate between two- and three-body LLNP decays, as well as the prospects for reconstructing the underlying model parameters.

   hep-phPLB(2019)·8 citations
3. 03*

   A global study of the extended scalar singlet model

   Ankit Beniwal🇸🇪 · Marek Lewicki🇬🇧 · Martin White🇦🇺 · Anthony G. Williams🇦🇺

   We present preliminary results from a global study of the extended scalar singlet model with a fermionic dark matter (DM) candidate. In addition to requiring a successful electroweak baryogenesis, we combine constraints from the DM relic density, direct detection limits from PandaX-II experiment, electroweak precision observables and Higgs searches at colliders. In agreement with previous studies, we find that the model can simultaneously explain (at least a part of) the observed DM abundance and matter-antimatter asymmetry. The viable points often lead to strong gravitational wave (GW) signals that can potentially be probed at future GW experiments.

   hep-phastro-ph.CO1 citation
4. 04*

   Lepton non-universality in $B$ decays and fermion mass structure

   B. Grinstein🇺🇸 · S. Pokorski🇵🇱 · G.G. Ross🇬🇧

   We consider the possibility that the neutral-current $B$ anomalies are due to radiative corrections generated by Yukawa interactions of quarks and leptons with new vector-like quark and lepton electroweak doublets and new Standard Model singlet scalars. We show that the restricted interactions needed can result from an underlying Abelian family symmetry and that the same symmetry can give rise to an acceptable pattern of quark and charged lepton masses and mixings, providing a bridge between the non-universality observed in the B-sector and that of the fermion mass matrices. We construct two simple models, one with a single singlet scalar in which the flavour changing comes from quark and lepton mixing and one with an additional scalar in which the flavour changing can come from both fermion and scalar mixing. We show that for the case the new quarks are much heavier than the new leptons and scalars the $B$ anomalies can be due to box diagrams with couplings in the perturbative regime consistent with the bounds coming from $B_s-{\bar{B}}_s$, $K-\bar{K}$ and $D-\bar{D}$ mixing as well as other lepton family number violating processes. The new states can be dark matter candidates and, in the two scalar model with a light scalar of O(60) GeV and vector-like lepton of O(100) GeV, there can be a simultaneous explanation of the B-anomalies, the muon anomalous magnetic moment and the dark matter abundance.

   hep-phJHEP(2018)·40 citations
5. 05*

   Standard Model Theory for the FCC-ee Tera-Z stage

   A. Blondel🇨🇭 · J. Gluza🇵🇱 · S. Jadach🇵🇱 · P. Janot🇨🇭 · T. Riemann🇵🇱 · A. Akhundov🇪🇸 · A. Arbuzov🇷🇺 · R. Boels🇩🇪 · S. Bondarenko🇷🇺 · S. Borowka🇨🇭 · C.M. Carloni Calame🇮🇹 · I. Dubovyk🇩🇪 and 26 other authors

   The future 100-km circular collider FCC at CERN is planned to operate in one of its modes as an electron-positron FCC-ee machine. We give an overview comparing the theoretical status to the experimental demands of one of four foreseen FCC-ee operating stages, Z-boson resonance energy physics, called the FCC-ee Tera-Z stage for short. The FCC-ee Tera-Z will deliver the highest integrated luminosities as well as very small systematic errors for a study of the Standard Model (SM) with unprecedented precision. In fact, the FCC-ee Tera-Z will allow the study of at least one more perturbative order in quantum field theory compared to the LEP/SLC precision. The real problem is that the present precision of theoretical calculations of the various SM observables does not match that of the anticipated experimental measurements. The bottle-necks to overcoming this situation are identified. In particular, the issues of precise QED unfolding and the correct calculation of SM pseudo-observables are critically reviewed. In an Executive Summary, we specify which basic theoretical calculations are needed to meet the strong experimental expectations at the FCC-ee Tera-Z. Several methods, techniques and tools needed for higher-order multi-loop calculations are presented. By inspection of the Z-boson partial and total decay width analyses, it is argued that at the beginning of operation of the FCC-ee Tera-Z, the theory predictions may be tuned to be precise enough not to limit the physics interpretation of the measurements. This statement is based on anticipated progress in analytical and numerical calculations of multi-loop and multi-scale Feynman integrals and on the completion of two-loop electroweak radiative corrections to the SM pseudo-observables this year. However, the above statement is conditional as the theoretical issues demand a very dedicated and focused investment by the community.

   hep-phCERN Yellow Rep. Monogr. 3 (2019)·106 citations
6. 06*

   Confinement and chiral phase transitions in QCD and superQCD

   Renata Jora🇷🇴

   We study confinement and chiral symmetry breaking phase transitions for QCD and supersymmetric QCD. The method is based on some justified assumption regarding the behavior of the Green function relevant for the potential between two charges or a gap equation. We determine the number of flavors at which the transitions to confinement and chiral symmetry breaking take place. We find that whereas for chiral symmetry breaking the results are in perfect agreement with those in the literature for confinement the situation is more complex.

   hep-ph1 citation
7. 07*

   Multiplicative renormalizability of quasi-parton operators

   Zheng-Yang Li🇨🇳 · Yan-Qing Ma🇨🇳 · Jian-Wei Qiu🇺🇸

   Extracting parton distribution functions (PDFs) from lattice QCD calculation of quasi-PDFs has been actively pursued in recent years. We extend our proof of the multiplicative renormalizability of quasi-quark operators in Ref. [1] to quasi-gluon operators, and demonstrated that quasi-gluon operators could be multiplicatively renormalized to all orders in perturbation theory, without mixing with other operators. We find that using a gauge-invariant UV regulator is essential for achieving this proof. With the multiplicative renormalizability of both quasi-quark and quasi-gluon operators, and QCD collinear factorization of hadronic matrix elements of there operators into PDFs, extracting PDFs from lattice QCD calculated hadronic matrix elements of quasi-parton operators could have a solid theoretical foundation.

   hep-phhep-latnucl-thPRL(2019)·87 citations
8. 08*

   A revision of radiative corrections to double-Dalitz decays

   Pablo Sanchez-Puertas🇨🇿 · K. Kampf🇨🇿 · J. Novotný🇨🇿

   The radiative corrections to double-Dalitz ($P\to \bar{\ell }\ell \overline{{\ell }^{\prime }}{\ell }^{\prime }$) decays are revisited and completed up to next-to-leading order in QED, finding mild differences with respect to previous studies. These might be relevant for extracting information about the mesons transition form factors, which play an important role in determining the hadronic light-by-light contribution to the anomalous magnetic moment of the muon.

   hep-phEPJ Web Conf.(2019)·1 citation
9. 09*

   Decay and Detection of a Light Scalar Boson Mixing with the Higgs

   Martin Wolfgang Winkler🇸🇪

   The simplest extension of the standard model consists in adding one singlet scalar field which mixes with the Higgs boson. O(GeV) masses of the new scalar carry strong motivation from relaxion, dark matter and inflation models. The decay of a GeV scalar is, however, notoriously difficult to address since, at this mass scale, the chiral expansion breaks down and perturbative QCD does not apply. Existing estimates of the GeV scalar decay rate disagree by several orders of magnitude. In this work, we perform a new dispersive analysis in order to strongly reduce these uncertainties and to resolve discrepancies in earlier results. We will update existing limits on light scalars and future experimental sensitivities which are in some cases strongly affected by the new-found decay rates. The meson form factors provided in this work, can be used to generalize our findings to non-universally coupled light scalars.

   hep-phPRD(2019)·280 citations
10. 10*

    Probing Top Quark FCNC tqgamma and tqZ Couplings at Future Electron-Proton Colliders

    O. Cakir (Ankara University)🇹🇷 · A. Yilmaz (Giresun University)🇹🇷 · I. Turk Cakir (Giresun University)🇹🇷 · A. Senol (Bolu Abant Izzet Baysal University)🇹🇷 · H. Denizli (Bolu Abant Izzet Baysal University)🇹🇷

    The top quark flavor changing neutral current (FCNC) processes are extremely suppressed within the Standard Model (SM) of particle physics. However, they could be enhanced in a new physics model Beyond the Standard Model (BSM). The top quark FCNC interactions would be a good test of new physics at present and future colliders. Within the framework of the BSM models, these interactions can be described by an effective Lagrangian. In this work, we study tqgamma and tqZ effective FCNC interaction vertices through the process e-p->e-Wq+X at future electron proton colliders, projected as Large Hadron electron Collider (LHeC) and Future Circular Collider-hadron electron (FCC-he). The cross sections for the signal have been calculated for different values of parameters lambda_q for tqgamma vertices and kappa_q for $tqZ$ vertices. Taking into account the relevant background we estimate the attainable range of signal parameters as a function of the integrated luminosity and present contour plots of couplings for different significance levels including detector simulation.

    hep-phNPB(2019)·17 citations
11. 11*

    Regge phenomenology of the $N^{\ast }$ and ${\Delta }^{\ast }$ poles

    JPAC collaboration: J.A. Silva-Castro🇲🇽 · C. Fernandez-Ramirez🇲🇽 · M. Albaladejo🇺🇸 · I.V. Danilkin🇩🇪 · A. Jackura🇺🇸 · V. Mathieu🇺🇸 · J. Nys🇧🇪 · A. Pilloni🇺🇸 · A.P. Szczepaniak🇺🇸 · G. Fox🇺🇸

    We use Regge phenomenology to study the structure of the poles of the $N^{\ast }$ and ${\Delta }^{\ast }$ spectrum. We employ the available pole extractions from partial wave analysis of meson scattering and photoproduction data. We assess the importance of the imaginary part of the poles (widths) to obtain a consistent determination of the parameters of the Regge trajectory. We compare the several pole extractions and show how Regge phenomenology can be used to gain insight in the internal structure of baryons. We find that the majority of the states in the parent Regge trajectories are compatible with a mostly compact three-quark state picture.

    hep-phnucl-thPRD(2019)·16 citations
12. 12*

    Search for the electromagnetic moments of the $\tau$ lepton in photon-photon collisions at the LHeC and the FCC-he

    M. Köksal🇹🇷

    We examine the potential of the process $ep\to e{\gamma }^{\ast }{\gamma }^{\ast }p\to e\tau \bar{\tau }p$ at the Large Hadron Electron Collider (LHeC) and the Future Circular Hadron Electron Collider (FCC-he) to examine non-standard $\tau \bar{\tau }\gamma$ coupling in a model independent way by means of the effective Lagrangian approach. We perform pure leptonic and semileptonic decays for ${\tau }^{-}{\tau }^{+}$ production in the final state. Furthermore, we use $L=10,50,100,300,500,1000$ fb${}^{-1}$ with at $\sqrt{s}=1.30,1.98,7.07,10$ TeV and we consider systematic uncertainties of ${\delta }_{sys}=0,5,10\%$. The best sensitivity bounds obtained from the process $ep\to e{\gamma }^{\ast }{\gamma }^{\ast }p\to e\tau \bar{\tau }p$ on the anomalous couplings are $-0.0025<{\tilde{a}}_{\tau }<0.0009$ and $|\widetilde{d_{\tau }}|<8.85\times 10^{-18}ecm$, respectively. Therefore, our results show that the process $ep\to e{\gamma }^{\ast }{\gamma }^{\ast }p\to e\tau \bar{\tau }p$ at the LHeC and FCC-he are a very good prospect for probing the anomalous magnetic and electric dipole moments of the $\tau$ lepton at ${\gamma }^{\ast }{\gamma }^{\ast }$ mode of the future $ep$ collider.

    hep-phJ.Phys.G(2019)·24 citations
13. 13*

    QCD at high density: Equation of state for nuclear collisions and neutron stars

    Anton Motornenko🇩🇪 · Volodymyr Vovchenko🇩🇪 · Jan Steinheimer🇩🇪 · Stefan Schramm🇩🇪 · Horst Stoecker🇩🇪

    A unified chiral mean field approach is presented for QCD thermodynamics in a wide range of temperatures and densities. The model simultaneously gives a satisfactory description of lattice QCD thermodynamics and fulfills nuclear matter and astrophysical constraints. The resulting equation of state can be incorporated in relativistic fluid-dynamical simulations of heavy-ion collisions and neutron stars mergers. Access to different regions of the QCD phase diagram can be obtained in simulations of heavy-ion data and observations of neutron star mergers.

    hep-phastro-ph.HEnucl-thNPA(2019)·15 citations
14. 14*

    Structure of Forward pp and pp̄ Elastic Amplitudes at Low Energies

    E. Ferreira🇧🇷 · A. K. Kohara🇧🇷 · J. Sesma🇪🇸

    Exact analytical forms of solutions for Dispersion Relations for Amplitudes and Dispersion Relations for Slopes are applied in the analysis of pp and $\mathrm{p}\bar{\mathrm{p}}$ scattering data in the forward range at energies below $\sqrt{(}s)\approx 30\text{GeV}$. As inputs for the energy dependence of the imaginary part, use is made of analytic form for the total cross sections and for parameters of the $t$ dependence of the imaginary parts, with exponential and linear factors. A structure for the $t$ dependence of the real amplitude is written, with slopes $B_R$ and a linear factor $\rho -{\mu }_{R}t$ that allows compatibility of the data with the predictions from dispersion relations for the derivatives of the real amplitude at the origin. A very precise description is made of all $d\sigma /dt$ data, with regular energy dependence of all quantities. It is shown that a revision of previous calculations of total cross sections, slopes and $\rho$ parameters in the literatures is necessary, and stressed that only determinations based on $d\sigma /dt$ data covering sufficient $t$ range using appropriate forms of amplitudes can be considered as valid.

    hep-phhep-exPRD(2018)·10 citations
15. 15*

    Gluon TMDs and NRQCD matrix elements in $J/\psi$ production at an EIC

    Alessandro Bacchetta🇮🇹 · Daniël Boer🇳🇱 · Cristian Pisano🇮🇹 · Pieter Taels🇮🇹

    In this paper we analyze azimuthal asymmetries in the processes of unpolarized and polarized $J/\psi ({\rm Y})$ production at an Electron-Ion Collider. Apart from giving access to various unknown gluon transverse momentum distributions, we suggest to use them as a new method to extract specific color-octet NRQCD long-distance matrix elements, i.e.\ $⟨0|{\mathcal{O}}_8^{J/\psi }{(}^1{S}_0)|0⟩$ and $⟨0|{\mathcal{O}}_8^{J/\psi }{(}^3{P}_0)|0⟩$, whose values are still quite uncertain and for which lattice calculations are unavailable. The new method is based on combining measurements of analogous asymmetries in open heavy-quark pair production which can be performed at the same energy. To enhance the gluon contribution one can consider smaller values of $x$ and, in order to assess the impact of small-$x$ evolution, we perform a numerical study using the MV model as a starting input and evolve it with the JIMWLK equations.

    hep-phEPJC(2020)·73 citations
16. 16*

    Spontaneous proton decay and the origin of Peccei-Quinn symmetry

    Mario Reig🇪🇸 · Rahul Srivastava🇪🇸

    We propose a new interpretation of Peccei-Quinn symmetry within the Standard Model, identifying it with the axial $B+L$ symmetry i.e. $U(1{)}_{PQ}\equiv U(1{)}_{{\gamma }_5(B+L)}$. This new interpretation retains all the attractive features of Peccei-Quinn solution to strong CP problem but in addition also leads to several other new and interesting consequences. Owing to the identification $U(1{)}_{PQ}\equiv U(1{)}_{{\gamma }_5(B+L)}$ the axion also behaves like Majoron inducing small seesaw masses for neutrinos after spontaneous symmetry breaking. Another novel feature of this identification is the phenomenon of spontaneous (and also chiral) proton decay with its decay rate associated with the axion decay constant. Low energy processes which can be used to test this interpretation are pointed out.

    hep-phPLB(2019)·13 citations
17. 17*

    Combined collider constraints on neutralinos and charginos

    The GAMBIT Collaboration: Peter Athron🇦🇺 · Csaba Balázs🇦🇺 · Andy Buckley🇬🇧 · Jonathan M. Cornell🇨🇦 · Matthias Danninger🇨🇦 · Ben Farmer🇬🇧 · Andrew Fowlie🇦🇺 · Tomás E. Gonzalo🇳🇴 · Julia Harz🇫🇷 · Paul Jackson🇦🇺 · Rose Kudzman-Blais🇨🇦 · Anders Kvellestad🇬🇧 and 8 other authors

    Searches for supersymmetric electroweakinos have entered a crucial phase, as the integrated luminosity of the Large Hadron Collider is now high enough to compensate for their weak production cross-sections. Working in a framework where the neutralinos and charginos are the only light sparticles in the Minimal Supersymmetric Standard Model, we use gambit to perform a detailed likelihood analysis of the electroweakino sector. We focus on the impacts of recent ATLAS and CMS searches with 36 fb${}^{-1}$ of 13 TeV proton-proton collision data. We also include constraints from LEP and invisible decays of the $Z$ and Higgs bosons. Under the background-only hypothesis, we show that current LHC searches do not robustly exclude any range of neutralino or chargino masses. However, a pattern of excesses in several LHC analyses points towards a possible signal, with neutralino masses of $(m_{{\tilde{\chi }}_1^0},m_{{\tilde{\chi }}_2^0},m_{{\tilde{\chi }}_3^0},m_{{\tilde{\chi }}_4^0})$ = (8-155, 103-260, 130-473, 219-502) GeV and chargino masses of $(m_{{\tilde{\chi }}_1^{\pm }},m_{{\tilde{\chi }}_2^{\pm }})$ = (104-259, 224-507) GeV at the 95% confidence level. The lightest neutralino is mostly bino, with a possible modest Higgsino or wino component. We find that this excess has a combined local significance of $3.3\sigma$, subject to a number of cautions. If one includes LHC searches for charginos and neutralinos conducted with 8 TeV proton-proton collision data, the local significance is lowered to 2.9$\sigma$. We briefly consider the implications for dark matter, finding that the correct relic density can be obtained through the Higgs-funnel and $Z$-funnel mechanisms, even assuming that all other sparticles are decoupled. All samples, gambit input files and best-fit models from this study are available on Zenodo.

    hep-phastro-ph.COEPJC(2019)·114 citations
18. 18*

    Radiative spin polarization in an ultrastrong magnetic field

    Koen van Kruining🇩🇪 · Felix Mackenroth🇩🇪 · Jörg B. Götte🇬🇧

    We calculate the spin flip rates for an electron in a homogeneous magnetic field for low excitations ($N\le 5$). Our results apply for all field strengths including those beyond the critical field strength at which the spin contributes as much to the electron's energy as its rest mass. Existing approximations either assume that the electron is in a sufficiently highly excited state such that its orbit can be assumed to be classical or the magnetic field be weak compared to the critical field. The regime of high magnetic field strength and low excitations is therefore poorly covered by them. By comparing our calculations to different approximations, we find that in the high field, low excitation regime the spin flip rates are lower and the equilibrium spin polarization is less pure then one would get by naively applying existing approximations in this regime.

    hep-phcond-mat.mes-hallhep-thPRD(2019)·11 citations
19. 19*

    The Direct Coupling of Light Quarks to Heavy Di-quarks

    Haipeng An🇨🇳 · Mark B. Wise🇺🇸

    In the limit $m_Q>m_Q{v}_{\mathrm{rel}}>m_Q{v}_{\mathrm{rel}}^2\gg {\Lambda }_{QCD}$ hadronic states with two heavy quarks $Q$ should be describable by a version of HQET where the heavy quark is replaced by a di-quark degree of freedom. In this limit the di-quark is a small (compared with $1/{\Lambda }_{QCD}$) color anti-triplet, bound primarily by a color Coulomb potential. The excited Coulombic states and color six states are much heavier than the color anti-triplet ground state. The low lying spectrum of hadrons containing two heavy quarks is then determined by the coupling of the light quarks and gluons with a momentum of order ${\Lambda }_{QCD}$ to this ground state di-quark. In this short paper we calculate the coefficient of leading local operator $\left(S_v^{†}{S}_v\right)\left(\bar{q}{\gamma }^{\mu }{v}_{\mu }q\right)$ that couples this color-triplet di-quark field $S_v$ (with four-velocity $v$) directly to the light quarks $q$ in the low energy effective theory. It is $\mathcal{O}(1/({\alpha }_s(m_Q{v}_{\mathrm{rel}})m_Q^2))$. While our work is mostly of pedagogical value we make an estimate of the contribution of this operator to the masses of ${\Xi }_{bbq}$ baryon and $T_{QQ\bar{q}\bar{q}}$ tetraquark using the non-relativistic constituent quark model.

    hep-phPLB(2019)·9 citations
20. 20*

    SUSY-like relation of the splitting functions in evolution of gluon and quark jet multiplicities

    Anatoly Kotikov🇷🇺

    We show the new relationship [1] between the anomalous dimensions, resummed through next-to-next-to-leading-logarithmic order, in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution equations for the first Mellin moments D_{q,g}(mu2) of the quark and gluon fragmentation functions, which correspond to the average hadron multiplicities in jets initiated by quarks and gluons, respectively. So far, such relationships have only been known from supersymmetric (SUSY) QCD. Exploiting available next-to-next-to-next-to-leading-order (NNNLO) information on the ratio D_g^+(mu2)/D_q^+(mu2) of the dominant plus components, the fit of the world data of D_{q,g}(mu2) for charged hadrons measured in e+e- annihilation leads to alpha_s^{(5)}(MZ)=0.1205 + 0.0016 - 0.0020.

    hep-phEPJ Web Conf.(2018)·2 citations
21. 21*

    Polarization amplitudes in ${\tau }^{-}\to {\nu }_{\tau }VP$ decay beyond the standard model

    L. R. Dai🇨🇳 · E. Oset🇪🇸

    We use a recent formalism of the weak hadronic reactions ${\tau }^{-}\to {\nu }_{\tau }{M}_1{M}_2$ to study the helicity amplitudes in ${\tau }^{-}\to {\nu }_{\tau }VP$ decay. This recent formalism maps the transition matrix elements at the quark level into hadronic matrix elements, and finally writes the weak matrix elements in terms of easy analytical formulas evaluated by means of an elaborate angular momentum algebra. The formalism provides directly the amplitudes for the different spin third components of the vector mesons involved. We extend the formalism to a general case, with the operator ${\gamma }^{\mu }-\alpha {\gamma }^{\mu }{\gamma }_5$, that can account for different models beyond the standard model and study in detail the ${\tau }^{-}\to {\nu }_{\tau }{K}^{\ast 0}{K}^{-}$ reaction for the different helicities of the $K^{\ast 0}$. The results are shown in terms of the $\alpha$ parameter that differs for each model. We find that $\frac{d\Gamma }{d{M}_{\mathrm{inv}}^{(K^{\ast 0}{K}^{-})}}$ is very different for the different components $M=\pm 1,0$ and in particular the magnitude $\frac{d\Gamma }{d{M}_{\mathrm{inv}}^{(K^{\ast 0}{K}^{-})}}{|}_{M=+1}-\frac{d\Gamma }{d{M}_{\mathrm{inv}}^{(K^{\ast 0}{K}^{-})}}{|}_{M=-1}$ is very sensitive to the $\alpha$ parameter, which makes the investigation of this magnitude a most welcome initiative to test different models beyond the standard model.

    hep-phEPJA(2018)·4 citations
22. 22*

    Probing color reconnection with underlying event observables at the LHC energies

    Antonio Ortiz🇲🇽 · Lizardo Valencia Palomo🇲🇽

    In this work we study the underlying event (UE) activity as a function of the highest jet transverse momentum ($p_{\mathrm{T}}^{\mathrm{jet}}$) in terms of the number and summed $p_{\mathrm{T}}$ densities of charged particles in the azimuthal region transverse to the $p_{\mathrm{T}}^{\mathrm{jet}}$ direction. The UE observables normalised to the INEL multiplicity obey an approximate Koba-Nielsen-Olesen (KNO) scaling. Based on PYTHIA~8.2 simulations of $pp$ collisions at LHC energies, we show that the remaining imperfection of the KNO scaling is due to the increasing importance of multiple partonic interactions (MPI) at higher $\sqrt{s}$. Motivated by this, we studied the UE activity considering charged particles within different $p_{\mathrm{T}}$ intervals in $pp$ collisions at $\sqrt{s}=7$\,TeV. We demonstrate that the saturations of both number and summed $p_{\mathrm{T}}$ densities, which are commonly claimed, are only observed for low-\pt charged particles ($0.5<p_{\mathrm{T}}<2$\,GeV/$c$). Moreover, for the $p_{\mathrm{T}}$-integrated case ($p_{\mathrm{T}}>0.5$\,GeV/$c$) the summed $p_{\mathrm{T}}$ density is not sensitive to the variation of color reconnection (CR), however at low-p_{\rm T} it is reduced with increasing CR, whereas an opposite behaviour is found at intermediate-$p_{\mathrm{T}}$ ($2<p_{\mathrm{T}}<10$\,GeV/$c$). Finally, we show that CR produces flow-like behaviour only in the UE region and the effects are reduced with increasing $p_{\mathrm{T}}^{\mathrm{jet}}$ due to the hardering of UE. The outcomes encourage the measurement of inclusive and identified charged particle $p_{\mathrm{T}}$ spectra (over a wide range of $p_{\mathrm{T}}$) associated to UE aimed at better understanding the similarities between $pp$ and heavy-ion data discovered at the LHC.

    ↳ hep-exhep-phnucl-exPRD(2019)·25 citations
23. 23*

    Harmonizing discovery thresholds and reporting two-sided confidence intervals: a modified Feldman & Cousins method

    Knut Dundas Morå🇸🇪

    When searching for new physics effects, collaborations will often wish to publish upper limits and intervals with a lower confidence level than the threshold they would set to claim an excess or a discovery. However, confidence intervals are typically constructed to provide constant coverage, or probability to contain the true value, with possible overcoverage if the random parameter is discrete. In particular, that means that the confidence interval will contain the $0$-signal case with the same frequency as the confidence level. This paper details a modification to the Feldman-Cousins method to allow a different, higher excess reporting significance than the interval confidence level.

    ↳ physics.data-anhep-exhep-phJINST(2019)·3 citations
24. 24*

    GANs for generating EFT models

    Harold Erbin🇩🇪 · Sven Krippendorf🇩🇪

    We initiate a way of generating models by the computer, satisfying both experimental and theoretical constraints. In particular, we present a framework which allows the generation of effective field theories. We use Generative Adversarial Networks to generate these models and we generate examples which go beyond the examples known to the machine. As a starting point, we apply this idea to the generation of supersymmetric field theories. In this case, the machine knows consistent examples of supersymmetric field theories with a single field and generates new examples of such theories. In the generated potentials we find distinct properties, here the number of minima in the scalar potential, with values not found in the training data. We comment on potential further applications of this framework.

    ↳ cs.LGhep-phhep-thPLB(2020)·40 citations
25. 25*

    Brans-Dicke cosmology mimicking running vacuum

    Javier de Cruz Perez🇪🇸 · Joan Sola🇪🇸

    Brans-Dicke (BD) cosmology is reconsidered from an approach in which the model can be formulated in $\Lambda$CDM form, but at the expense of replacing the rigid cosmological constant $\Lambda$ with a dynamical quasivacuum component which depends on a small parameter $ϵ$. The product of $ϵ$ times the BD-parameter ${\omega }_{\mathrm{BD}}$ becomes exactly determined in terms of the ordinary cosmological parameters. The GR limit is recovered for ${\omega }_{\mathrm{BD}}\to \infty$ when $ϵ\to 0$. We solve the background cosmology of the model as well as the perturbations equations. When fitted to the cosmological data, we find that the BD-cosmology, transcribed in such an effective GR form, appears to be competitive with the $\Lambda$CDM and emulates the running vacuum model.

    ↳ gr-qcastro-ph.COhep-phhep-thMod.Phys.Lett.A(2018)·39 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.