Wed·Oct 30, 2019Wednesday·October 30, 2019

1. 01*

   Why matter effects matter for JUNO

   Amir N. Khan🇩🇪 · Hiroshi Nunokawa🇧🇷 · Stephen J. Parke🇺🇸

   In this paper we focus on the Earth matter effects for the solar parameter determination by a medium baseline reactor experiment such as JUNO. We derive perturbative expansions for the mixing angles ${\theta }_{12}$ and ${\theta }_{13}$ as well as the $\Delta m_{21}^2$ and $\Delta m_{31}^2$ in terms of the matter potential relevant for JUNO. These expansions, up to second order in the matter potential, while simple, allow one to calculate the electron antineutrino survival probability to a precision much better than needed for the JUNO experiment. We use these perturbative expansions to semi-analytically explain and confirm the shift caused by the matter effects on the solar neutrino mixing parameters ${\theta }_{12}$ and $\Delta m_{21}^2$ which were previously obtained by a purely numerical ${\chi }^2$ analysis. Since these shifts do not satisfy the naive expectations and are significant given the precision that can be achieved by the JUNO experiment, a totally independent cross check using a completely different method is of particular importance. We find that these matter effect shifts do not depend on any of the details of the detector characteristics apart from the baseline and earth mass density between reactor(s) and detector, but do depend on the normalized product of reactor neutrino spectrum times the inverse-beta decay cross-section. The results of this manuscript suggests an alternative analysis method for measuring ${\sin }^2{\theta }_{12}$ and $\Delta m_{21}^2$ in JUNO which would be a useful cross check of the standard analysis and for the understanding of the Wolfenstein matter effect. The explanation of these shifts together with a quantitative understanding, using a semi-analytical method, is the principal purpose of this paper.

   hep-phhep-exPLB(2020)·32 citations
2. 02*

   Cosmoparticle physics of dark matter

   Maxim Khlopov🇷🇺

   The lack of confirmation for the existence of supersymmetric particles and Weakly Interacting Massive Particles (WIMPs) appeals to extension of the field of studies of the physical nature of dark matter, involving non-supersymmetric and non-WIMP solutions. We briefly discuss some examples of such candidates in their relationship with extension of particle symmetry and pattern of symmetry breaking. We specify in the example of axion-like particles nontrivial features of cosmological reflection of the structure and pattern of Peccei-Quinn-like symmetry breaking. The puzzles of direct and indiect dark matter searches can find solution in the approach of composite dark matter. The advantages and open problems of this approach are specified. We note that detailed analysis of cosmological consequences of any extension of particle model that provides candidates for dark matter inevitably leads to nonstandard features in the corresponding cosmological scenario. It makes possible to use methods of cosmoparticle physics to study physical nature of the dark matter in the combination of its physical, astrophysical and cosmological signatures.

   hep-phastro-ph.COhep-thEPJ Web Conf.(2019)·6 citations
3. 03*

   Minimal Seesaw extension for Neutrino Mass and Mixing, Leptogenesis and Dark Matter: FIMPzillas through the Right-Handed Neutrino Portal

   Marco Chianese🇳🇱 · Bowen Fu🇬🇧 · Stephen F. King🇬🇧

   We propose a minimal seesaw extension to simultaneously account for realistic neutrino mass and mixing, the baryon asymmetry of the Universe via leptogenesis and a viable dark matter relic density, in which two right-handed neutrinos are coupled to a dark Dirac fermion and complex scalar field, both charged under a global $U(1{)}_D$ symmetry. As a concrete example, we consider the Littlest Seesaw model which describes neutrino mass and mixing and accounts for leptogenesis, thereby fixing the neutrino Yukawa couplings and right-handed neutrino masses. By considering the freeze-in production mechanism of dark matter, we explore the parameter space of right-handed neutrino portal couplings and dark particle masses which give the correct dark matter relic abundance, focussing on the case of a superheavy Dirac fermion dark matter particle, with a mass around $10^{10}$ GeV. Such a FIMPzilla can provide a successful explanation of the dark matter relic abundance, with its production reliant on neutrino Yukawa couplings over much of the parameter space, depending on the assumed dark particle masses, and the reheat temperature.

   hep-phJCAP(2020)·52 citations
4. 04*

   Probing dark matter signals in neutrino telescopes through angular power spectrum

   Ariane Dekker🇳🇱 · Marco Chianese🇳🇱 · Shin'ichiro Ando🇳🇱

   The hypothesis of two different components in the high-energy neutrino flux observed with IceCube has been proposed to solve the tension among different data-sets and to account for an excess of neutrino events at 100 TeV. In addition to a standard astrophysical power-law component, the second component might be explained by a different class of astrophysical sources, or more intriguingly, might originate from decaying or annihilating dark matter. These two scenarios can be distinguished thanks to the different expected angular distributions of neutrino events. Neutrino signals from dark matter are indeed expected to have some correlation with the extended galactic dark matter halo. In this paper, we perform angular power spectrum analyses of simulated neutrino sky maps to investigate the two-component hypothesis with a contribution from dark matter. We provide current constraints and expected sensitivity to dark matter parameters for future neutrino telescopes such as IceCube-Gen2 and KM3NeT. The latter is found to be more sensitive than IceCube-Gen2 to look for a dark matter signal at low energies towards the galactic center. Finally, we show that after 10 years of data-taking, they will firmly probe the current best-fit scenario for decaying dark matter by exploiting the angular information only.

   hep-phastro-ph.COastro-ph.HEJCAP(2020)·27 citations
5. 05*

   Charming New $B$-Physics

   S. Jäger🇬🇧 · M. Kirk🇮🇹 · A. Lenz🇬🇧 · K. Leslie🇬🇧

   We give a comprehensive account of the flavour physics of Beyond-Standard-Model (BSM) effects in $b\to c\bar{c}s$ transitions, considering the full set of 20 four-quark operators. We discuss the leading-order structure of their RG mixing with each other as well as the QCD-penguin, dipole, and FCNC semileptonic operators they necessarily mix with, providing compact expressions. We also provide the first complete results for BSM effects in the lifetime observables $\Delta {\Gamma }_s$ and $\tau (B_s)/\tau (B_d)$, as well as for the semileptonic CP-asymmetry $a_{sl}^s$. From a global analysis, we obtain stringent constraints on 16 of the 20 BSM operators, including the 10 operators $Q_{1\dots 10}^{c\prime }$ involving a right-handed strange quark. Focussing on CP-conserving new physics, the constraints correspond to NP scales of order 10 TeV in most cases, always dominated by exclusive and/or radiative $B$-decays via RGE mixing. For the remaining four operators, including the two Standard-Model (SM) ones, larger effects are experimentally allowed, as previously noted in arXiv:1701.09183. We extend that paper's scope to the CP-violating case, paying attention to the impact on the decay rate and time-dependent CP-violation in $B_d\to J/\psi K_S$. We show that quantifiable constraints arise for new physics in either of the two SM operators, with the uncertain non-perturbative matrix element of the colour-suppressed operator determined from the data. For new physics in the SM suppressed coefficient $C_1^c$ we find two perfectly viable, narrow bands of complex Wilson coefficients. Somewhat curiously, one of them contains a region where the fitted matrix element for the colour-suppressed operator is in agreement with naive factorization, contrarily to a widely held belief that large non-factorizable contributions to $B_d\to J/\psi K_S$ are implied by experimental data.

   hep-phJHEP(2020)·35 citations
6. 06*

   Stop Search in SUSY SO(10) GUTs with Nonuniversal Gaugino Masses

   Zafer Altin🇹🇷 · Zerrin Kirca🇹🇷 · Tugce Tanimak🇹🇷 · Cem Salih Un🇹🇷

   We have discussed the stop mass and possible signal processes within a class of SUSY GUTs with non-universal gaugino masses. This class of models predicts the stop mass in a wide range from about 400 GeV to 8 TeV, and the DM constraints bound it as $m_{{\tilde{t}}_1}\gtrsim 500$ GeV. Being the lightest supersymmetric particle the neutralino always takes part in possible signal processes, and its mass is realized as heavy as about 2.3 TeV in the fundamental parameter space. Similarly, the lightest chargino mass can be realized beyond 3 TeV, while the DM constraints bound its mass at about 2.7 TeV from above. We find that the stop mass below about 1.2 TeV is excluded by the analyses over the ${\tilde{t}}_1\to t{\tilde{\chi }}_1^0$ decay mode performed under the current experimental setups. This mode can help probe the stop mass up to about 6 TeV in future collider experiments. Similar analyses yield that the stop mass will be able to be probed to about 4.8 TeV and 5 TeV, if the ${\tilde{t}}_1\to b{W}^{\pm }{\tilde{\chi }}_1^0$ or ${\tilde{t}}_1\to bq{\bar{q}}^{\prime }{\tilde{\chi }}_1^0$ decay modes are allowed. We show that the former decay mode is not available for this class of SUSY GUTs in the current experiments, while it will be able to be tested in future.

   hep-ph1 citation
7. 07*

   Continuity and Semileptonic $B_{(s)}\to D_{(s)}$ Form Factors

   Andrew Kobach🇺🇸

   Small changes in the masses of massive external scattering states should correspond to small changes in the non-perturbative parameterization of form factors in quantum field theory, as long as the relevant energy range is not near strong deformations. Here, the definition of ``small'' is investigated and applied to $SU(3)$ breaking in semileptonic $B_{(s)}\to D_{(s)}$ transitions. When unitarity and analyticity are imposed, the differences in the form factors for semileptonic $B\to D$ versus $B_s\to D_s$ decays are found to be within $\mathcal{O}(1\%)$ over the entire kinematic range, not just at zero recoil, which is consistent with results from lattice calculations and differs from the expectation using HQET alone.

   hep-phhep-latPLB(2020)·9 citations
8. 08*

   Saturation and forward jets in proton-lead collisions at the LHC

   Heikki Mäntysaari🇫🇮 · Hannu Paukkunen🇫🇮

   We investigate the forward-jet energy spectrum within the Color Glass Condensate framework at 5 TeV center-of-mass energy. In particular, we focus on the kinematic range covered by the CMS-CASTOR calorimeter. We show that our saturation-model calculations are compatible with the CASTOR measurements and that to optimally reproduce the data, effects of multi-parton interactions need to be included. We predict a significant nuclear suppression - reaching down to 50% at the lowest considered jet energies $E_{\mathrm{jet}}\sim 500\mathrm{GeV}$.

   hep-phnucl-thPRD(2019)·22 citations
9. 09*

   Complex Scalar Dark Matter in G2HDM

   Chuan-Ren Chen🇹🇼 · Yu-Xiang Lin🇹🇼 · Chrisna Setyo Nugroho🇹🇼 · Raymundo Ramos🇹🇼 · Yue-Lin Sming Tsai🇹🇼 · Tzu-Chiang Yuan🇹🇼

   The complex scalar dark matter (DM) candidate in the gauged two Higgs doublet model (G2HDM), stabilized by a peculiar hidden parity ($h$-parity), is studied in detail. We explore the parameter space for the DM candidate by taking into account the most recent DM constraints from various experiments, in particular, the PLANCK relic density measurement and the current DM direct detection limit from XENON1T. We separate our analysis in three possible compositions for the mixing of the complex scalar. We first constrain our parameter space with the vacuum stability and perturbative unitarity conditions for the scalar potential, LHC Higgs measurements, plus Drell-Yan and electroweak precision test constraints on the gauge sector. We find that DM dominated by composition of the inert doublet scalar is completely excluded by further combining the previous constraints with both the latest results from PLANCK and XENON1T. We also demonstrate that the remaining parameter space with two other DM compositions can be further tested by indirect detection like the future CTA gamma-ray telescope.

   hep-phPRD(2020)·19 citations
10. 10*

    Light sterile neutrinos: oscillations and cosmology

    S. Gariazzo🇪🇸

    Light sterile neutrinos with a mass around 1 eV have been studied for many years as a possible explanation of the so called short-baseline neutrino oscillation anomalies. Recently, several neutrino oscillation experiments reported preferences for non-zero values of the mixing angles and squared mass differences for active-sterile mixing, which however are not always in agreement. I review our current knowledge of the light sterile neutrino in the 3+1 model, starting with a separate discussion on the status of the most relevant searches and then analyzing the problems that arise when combining different probes in a global fit. A short summary on the tension with cosmological observations is also provided.

    hep-phastro-ph.COActa Phys.Polon.B(2019)·1 citation
11. 11*

    Semileptonic $B_c$ meson decays to S-wave charmonium states

    Sonali Patnaik🇮🇳 · Lopamudra Nayak🇮🇳 · P. C. Dash🇮🇳 · Susmita Kar🇮🇳 · N. Barik🇮🇳

    We study the semileptonic decays of $B_c$ meson to S-wave charmonium states in the framework of relativistic independent quark model based on an average flavor-independent confining potential $U(r)$ in the scalar-vector harmonic form $U(r)=\frac{1}{2}(1+{\gamma }^0)(a{r}^2+V_0)$, where ($a$, $V_0$) are the potential parameters.The form factors for $B_c^{+}\to {\eta }_c/\psi e^{+}{\nu }_e$ transitions are studied in the physical kinematic range. Our predicted branching ratios (BR) for transitions to ground state charmonia are found comparatively large $\sim$ $10^{-2}$, compared to those for transitions to radially excited 2S and 3S states. Like all other mpdel predictions, our predicted BR are obtained in the hierarchy: BR($B_c^{+}\to {\eta }_c/\psi (3S)$) $<$ BR($B_c^{+}\to {\eta }_c/\psi (2S)$) $<$ BR($B_c^{+}\to {\eta }_c/\psi (1S)$). The longitudinal (${\Gamma }_L$) and transverse polarization (${\Gamma }_T$) for $B_c\to \psi (ns)$ decay modes are predicted in the small and large $q^2$ - region as well as in the whole physical region. The ratios for such transitions are obtained $\frac{{\Gamma }_L}{{\Gamma }_T}<1$ throughout the kinematic range which means the $B_c^{+}$ meson transitions to vector meson charmonium states take place predominantly in transverse polarization mode. The theoretical predictions on these transitions could be tested in the on-going and forthcoming experiments at LHCb.

    hep-phEur.Phys.J.Plus(2020)·15 citations
12. 12*

    A New Theory Framework for the Electroweak Radiative Corrections in $K_{l3}$ Decays

    Chien-Yeah Seng🇩🇪 · Daniel Galviz🇩🇪 · Ulf-G. Meißner🇩🇪

    We propose a new theory framework to study the electroweak radiative corrections in $K_{l3}$ decays by combining the classic current algebra approach with the modern effective field theory. Under this framework, the most important $\mathcal{O}(G_F\alpha )$ radiative corrections are described by a single tensor $T^{\mu \nu }$ involving the time-ordered product between the charged weak current and the electromagnetic current, and all remaining pieces are calculable order-by-order in Chiral Perturbation Theory. We further point out a special advantage in the $K_{l3}^0$ channel that it suffers the least impact from the poorly-constrained low-energy constants. This finding may serve as a basis for a more precise extraction of the matrix element $V_{us}$ in the future.

    hep-phhep-exnucl-exnucl-thJHEP(2020)·37 citations
13. 13*

    New evaluation of axial nucleon form factor from electron- and neutrino-scattering data and impact on neutrino-nucleus cross-section

    G. D. Megias🇪🇸 · S. Bolognesi🇫🇷 · M. B. Barbaro🇮🇹 · E. Tomasi-Gustafsson🇫🇷

    A joint fit to neutrino-nucleon scattering and pion electroproduction data is performed to evaluate the nucleon axial form factor in the two-component model consisting of a three-quark intrinsic structure surrounded by a meson cloud. Further constrains on the model are obtained by re-evaluating the electromagnetic form factor using electron scattering data. The results of the axial form factor show sizable differences with respect to the widely used dipole model. The impact of such changes on the Charged-Current Quasi-Elastic neutrino-nucleus cross-section is evaluated in the SuSAv2 nuclear model, based on the Relativistic Mean Field and including the contribution of two-body currents. How the different parametrizations of the axial form factor affect the cross-section prediction is assessed in full details and comparisons to recent T2K and MINERvA data are presented.

    hep-phhep-exnucl-thPRC(2020)·23 citations
14. 14*

    Viscosity, non-conformal equation of state and sound velocity in Landau hydrodynamics

    Deeptak Biswas🇮🇳 · Kishan Deka🇮🇳 · Amaresh Jaiswal🇮🇳 · Sutanu Roy🇮🇳

    We find an analytical solution to relativistic viscous hydrodynamics for a 1+1 dimensional Landau flow profile. We consider relativistic Navier-Stokes form of the dissipative hydrodynamic equation, for a non-conformal system with a constant speed of sound, and employ the obtained solution to fit rapidity spectrum of observed pions in $\sqrt{s_{NN}}=$ 200, 17.3, 12.3, 8.76, 7.62, 6.27, 4.29, 3.83, 3.28 and 2.63 GeV collision energies. We find that at the freeze-out hypersurface with improved Landau's freeze-out prescription, the viscous corrections do not affect the rapidity spectra. We demonstrate that the solution of the non-conformal Landau flow lead to a better agreement with the experimental data compared to the conformal ideal solution. We also extract speed of sound from fit to the rapidity spectra for various collision energies and find a monotonous decrease with decreasing collision energies. Appealing to the fact that viscosity has negligible effect on rapidity spectra for Landau's freeze-out scenario, we argue that our calculations provides a framework for extracting the average value of speed of sound in relativistic heavy-ion collisions.

    hep-phhep-thnucl-thPRC(2020)·18 citations
15. 15*

    Spectroscopy, lifetime and decay modes of the $T_{bb}^{-}$ tetraquark

    E. Hernández🇪🇸 · J. Vijande🇪🇸 · A. Valcarce🇪🇸 · Jean-Marc Richard🇫🇷

    We present the first full-fledged study of the flavor-exotic isoscalar $T_{bb}^{-}\equiv bb\bar{u}\bar{d}$ tetraquark with spin and parity $J^P=1^{+}$. We report accurate solutions of the four-body problem in a quark model, characterizing the structure of the state as a function of the ratio $M_Q/m_q$ of the heavy to light quark masses. For such a standard constituent model, $T_{bb}^{-}$ lies approximately 150 MeV below the strong decay threshold $B^{-}{\overline{B^{\ast }}}^0$ and 105 MeV below the electromagnetic decay threshold $B^{-}{\bar{B}}^0\gamma$. We evaluate the lifetime of $T_{bb}^{-}$, identifying the promising decay modes where the tetraquark might be looked for in future experiments. Its total decay width is $\Gamma \approx 87\times 10^{-15}$ GeV and therefore its lifetime $\tau \approx$ 7.6 ps. The promising final states are ${B^{\ast }}^{-}{D^{\ast }}^{+}{\ell }^{-}{\bar{\nu }}_{\ell }$ and ${\overline{B^{\ast }}}^0{D^{\ast }}^0{\ell }^{-}{\bar{\nu }}_{\ell }$ among the semileptonic decays, and ${B^{\ast }}^{-}{D^{\ast }}^{+}{D_s^{\ast }}^{-}$, ${\overline{B^{\ast }}}^0{D^{\ast }}^0{D_s^{\ast }}^{-}$, and ${B^{\ast }}^{-}{D^{\ast }}^{+}{\rho }^{-}$ among the nonleptonic ones. The semileptonic decay to the isoscalar $J^P=0^{+}$ tetraquark $T_{bc}^0$ is also relevant but it is not found to be dominant. There is a broad consensus about the existence of this tetraquark, and its detection will validate our understanding of the low-energy realizations of Quantum Chromodynamics (QCD) in the multiquark sector.

    hep-phhep-exnucl-thPLB(2020)·62 citations
16. 16*

    Higgs vacuum (in)stability during inflation: the dangerous relevance of de Sitter departure and Planck-suppressed operators

    Jacopo Fumagalli🇫🇷 · Sébastien Renaux-Petel🇫🇷 · John W. Ronayne🇫🇷

    The measured Standard Model parameters lie in a range such that the Higgs potential, once extrapolated up to high scales, develops a minimum of negative energy density. This has important cosmological implications. In particular, during inflation, quantum fluctuations could have pushed the Higgs field beyond its potential barrier, triggering the formation of anti-de Sitter regions, with fatal consequences for our universe. By requiring that this did not happen, one can in principle connect (and constrain) Standard Model parameters with the energy scale of inflation. In this context, we highlight the sensitivity of the fate of our vacuum to seemingly irrelevant physics. In particular, the departure of inflation from an exact de Sitter phase, as well as Planck-suppressed derivative operators, can, already and surprisingly, play a decisive role in (de)stabilizing the Higgs during inflation. Furthermore, in the stochastic dynamics, we quantify the impact of the amplitude of the noise differing from the one of a massless field, as well as of going beyond the slow-roll approximation by using a phase-space approach. On a general ground, our analysis shows that relating the period of inflation to precision particle physics requires a knowledge of these "irrelevant" effects.

    hep-phastro-ph.COgr-qchep-thJHEP(2020)·36 citations
17. 17*

    Longitudinal short-distance constraints for the hadronic light-by-light contribution to $(g-2{)}_{\mu }$ with large-$N_c$ Regge models

    Gilberto Colangelo🇨🇭 · Franziska Hagelstein🇨🇭 · Martin Hoferichter🇺🇸 · Laetitia Laub🇨🇭 · Peter Stoffer🇺🇸

    While the low-energy part of the hadronic light-by-light (HLbL) tensor can be constrained from data using dispersion relations, for a full evaluation of its contribution to the anomalous magnetic moment of the muon $(g-2{)}_{\mu }$ also mixed- and high-energy regions need to be estimated. Both can be addressed within the operator product expansion (OPE), either for configurations where all photon virtualities become large or one of them remains finite. Imposing such short-distance constraints (SDCs) on the HLbL tensor is thus a major aspect of a model-independent approach towards HLbL scattering. Here, we focus on longitudinal SDCs, which concern the amplitudes containing the pseudoscalar-pole contributions from ${\pi }^0$, $\eta$, ${\eta }^{\prime }$. Since these conditions cannot be fulfilled by a finite number of pseudoscalar poles, we consider a tower of excited pseudoscalars, constraining their masses and transition form factors from Regge theory, the OPE, and phenomenology. Implementing a matching of the resulting expressions for the HLbL tensor onto the perturbative QCD quark loop, we are able to further constrain our calculation and significantly reduce its model dependence. We find that especially for the ${\pi }^0$ the corresponding increase of the HLbL contribution is much smaller than previous prescriptions in the literature would imply. Overall, we estimate that longitudinal SDCs increase the HLbL contribution by $\Delta a_{\mu }^{\text{LSDC}}=13(6)\times 10^{-11}$. This number does not include the contribution from the charm quark, for which we find $a_{\mu }^{c\text{-quark}}=3(1)\times 10^{-11}$.

    hep-phhep-exhep-latnucl-thJHEP(2020)·431 citations
18. 18*

    Combining Sterile Neutrino Fits to Short Baseline Data with IceCube Data

    M.H. Moulai🇺🇸 · C.A. Argüelles🇺🇸 · G.H. Collin🇺🇸 · J.M. Conrad🇺🇸 · A. Diaz🇺🇸 · M.H. Shaevitz🇺🇸

    Recent global fits to short-baseline neutrino oscillation data have been performed finding preference for a sterile neutrino solution (3+1) over null. In the most recent iteration, it was pointed out that an unstable sterile neutrino (3+1+decay) may be a better description of the data. This is due to the fact that this model significantly reduces the tension between appearance and disappearance datasets. In this work, we add a one-year IceCube dataset to the global fit obtaining new results for the standard 3+1 and 3+1+decay sterile neutrino scenarios. We find that the 3+1+decay model provides a better fit than the 3+1, even in the presence of IceCube, with reduced appearance to disappearance tension. The 3+1+decay model is a 5.4$\sigma$ improvement over the null hypothesis and a 2.8$\sigma$ improvement over the standard 3+1 model.

    hep-phhep-exPRD(2020)·40 citations
19. 19*

    Strong Supercooling as a Consequence of Renormalization Group Consistency

    Vedran Brdar🇩🇪 · Alexander J. Helmboldt🇩🇪 · Manfred Lindner🇩🇪

    Classically scale-invariant models are attractive not only because they may offer a solution to the long-standing gauge hierarchy problem, but also due to their role in facilitating strongly supercooled cosmic phase transitions. In this paper, we investigate the interplay between these two aspects. We do so in the context of the electroweak phase transition (EWPT) in the minimal scale-invariant theory. We find that the amount of supercooling generally decreases for increasing scalar couplings. However, the stabilization of the electroweak scale against the Planck scale requires the absence of Landau poles in the respective energy range. Scalar couplings at the TeV scale can therefore not become larger than $\mathcal{O}(10^{-1})$. As a consequence, all fully consistent parameter points predict the EWPT not to complete before the QCD transition, which then eventually triggers the generation of the electroweak scale. We also discuss the potential of the model to give rise to an observable gravitational wave signature, as well as the possibility to accommodate a dark matter candidate.

    hep-phastro-ph.COhep-thJHEP(2019)·26 citations
20. 20*

    QCD, from its inception to its stubbornly unsolved problems

    A. De Rújula🇪🇸

    Whenever one has witnessed some event and then sees it reported in the media, one's reaction is the same: "it was not quite like that". It is in this spirit of a frequent first-hand witness that I write this article. I discuss a few selected points which --to my judgement-- illustrate well the QCD evolution (in time) from the theoretical, phenomenological and experimental points of view.

    hep-phhep-thInt.J.Mod.Phys.A(2019)·5 citations
21. 21*

    Neutrino emission characteristics of black hole formation in three-dimensional simulations of stellar collapse

    Laurie Walk🇩🇰 · Irene Tamborra (Niels Bohr Institute)🇩🇰 · Hans-Thomas Janka🇩🇪 · Alexander Summa🇩🇪 · Daniel Kresse (MPA, Garching)🇩🇪

    Neutrinos are unique probes of core-collapse supernova dynamics, especially in the case of black hole (BH) forming stellar collapses, where the electromagnetic emission may be faint or absent. By investigating two 3D hydrodynamical simulations of BH-forming stellar collapses of mass 40 and 75 M_sun, we identify the physical processes preceding BH formation through neutrinos, and forecast the neutrino signal expected in the existing IceCube and Super-Kamiokande detectors, as well as in the future generation DUNE facility. Prior to the abrupt termination of the neutrino signal corresponding to BH formation, both models develop episodes of strong and long-lasting activity by the spiral standing accretion shock instability (SASI). We find that the spiral SASI peak in the Fourier power spectrum of the neutrino event rate will be distinguishable at 3 sigma above the detector noise for distances up to O(30) kpc in the most optimistic scenario, with IceCube having the highest sensitivity. Interestingly, given the long duration of the spiral SASI episodes, the spectrograms of the expected neutrino event rate carry clear signs of the evolution of the blue spiral SASI frequency as a function of time, as the shock radius and post-shock fluid velocity evolve. Due to the high accretion luminosity and its large-amplitude SASI-induced modulations, any contribution from asymmetric (dipolar or quadrupolar) neutrino emission associated with the lepton emission self-sustained asymmetry (LESA) is far subdominant in the neutrino signal.

    ↳ astro-ph.HEhep-phPRD(2020)·90 citations
22. 22*

    Role of U${}_A$(1) breaking term in dynamical chiral symmetry breaking of chiral effective theories

    Shinnosuke Kono (1,2)🇯🇵 · Daisuke Jido (2,1)🇯🇵 · Yoshiki Kuroda (3)🇯🇵 · Masayasu Harada (3) ((1) Tokyo Metropolitan University, (2) Tokyo Institute of Technology, (3) Nagoya University)🇯🇵

    The spontaneous breaking of chiral symmetry is examined by chiral effective theories, such as the linear sigma model and the Nambu Jona-Lasinio (NJL) model. Indicating that sufficiently large contribution of the UA(1) anomaly can break chiral symmetry spontaneously, we discuss such anomaly driven symmetry breaking and its implication. We derive a mass relation among the SU(3) flavor singlet mesons, eta0 and sigma0, in the linear sigma model to be satisfied for the anomaly driven symmetry breaking in the chiral limit, and find that it is also supported in the NJL model. With the explicit breaking of chiral symmetry, we find that the chiral effective models reproducing the observed physical quantities suggest that the sigma0 meson regarded as the quantum fluctuation of the chiral condensate should have a mass smaller than an order of 800 MeV when the anomaly driven symmetry breaking takes place.

    ↳ nucl-thhep-phPTEP(2021)·10 citations
23. 23*

    Perturbation theory of non-perturbative Yang-Mills theory: a massive expansion from first principles

    Giorgio Comitini🇮🇹

    The main objective of this thesis is to present a new analytical framework for low-energy QCD that goes under the name of massive, or "screened", perturbative expansion. The massive perturbative expansion is motivated by the phenomenon of dynamical mass generation, by which the gluons acquire a mass of the order of the QCD scale ${\Lambda }_{\text{QCD}}$ in the limit of vanishing momentum. It is a simple extension of ordinary perturbation theory that consists in a shift of the expansion point of the Yang-Mills perturbative series with the aim of treating the transverse gluons as massive already at tree-level, while leaving the total action of the theory unchanged. The new framework will be formulated in the context of pure Yang-Mills theory, where the lattice data is readily available for comparison and the perturbative results have been perfected by enforcing the gauge invariance of the analytical structure of the gluon propagator.

    ↳ hep-thhep-lathep-ph2 citations
24. 24*

    Equivalence between Horndeski and beyond Horndeski theories and imperfect fluids

    Israel Quiros🇲🇽 · Ulises Nucamendi🇲🇽 · Roberto De Arcia🇲🇽 · Tame Gonzalez🇲🇽 · Francisco Antonio Horta-Rangel🇲🇽

    In this paper we show that an equivalence between Horndeski and beyond Horndeski theories and general relativity with an effective imperfect fluid can be formally established. The formal equivalence is discussed for several particular cases of interest. Working in the cosmological framework, it is shown that, while the effective stress-energy tensor of viable Horndeski theories is formally equivalent to that of an imperfect fluid with anisotropic stresses and vanishing heat flux vector, the effective stress-energy tensor of beyond Horndeski theories is equivalent to the one of a perfect fluid instead.

    ↳ gr-qcastro-ph.COhep-phPRD(2020)·27 citations
25. 25*

    Flavour anomalies in $B$ decays at LHCb

    A. Hicheur🇧🇷

    The direct searches for Beyond Standard Model (BSM) particles have been constraining their mass scale to the extent where it is now becoming consensual that such particles are likely to be above the energy reach of the LHC. Meanwhile, the studies of indirect probes of BSM physics, with all their diversity, have been progressing both in accurracy and in setting up observables with reduced theoretical uncertainties. The observation of flavour anomalies in $b$ hadron decays represents an important part of the program of indirect detection of BSM physics. Several benchmark analyses involving leptonic or semileptonic decays are presented, with an emphasis on intriguing patterns which are systematic in their trend, though not individually significant yet.

    ↳ hep-exhep-phPoS(2020)·1 citation
26. 26*

    Detecting gravitational waves from cosmological phase transitions with LISA: an update

    Chiara Caprini🇫🇷 · Mikael Chala🇬🇧 · Glauber C. Dorsch🇺🇸 · Mark Hindmarsh🇫🇮 · Stephan J. Huber🇬🇧 · Thomas Konstandin🇩🇪 · Jonathan Kozaczuk🇺🇸 · Germano Nardini🇳🇴 · Jose Miguel No🇪🇸 · Kari Rummukainen🇫🇮 · Pedro Schwaller🇩🇪 · Geraldine Servant🇩🇪 · Anders Tranberg🇳🇴 · David J. Weir🇫🇮

    We investigate the potential for observing gravitational waves from cosmological phase transitions with LISA in light of recent theoretical and experimental developments. Our analysis is based on current state-of-the-art simulations of sound waves in the cosmic fluid after the phase transition completes. We discuss the various sources of gravitational radiation, the underlying parameters describing the phase transition and a variety of viable particle physics models in this context, clarifying common misconceptions that appear in the literature and identifying open questions requiring future study. We also present a web-based tool, PTPlot, that allows users to obtain up-to-date detection prospects for a given set of phase transition parameters at LISA.

    ↳ astro-ph.COhep-phJCAP(2020)·974 citations
27. 27*

    QCD phase diagram in chiral imbalance with self-consistent mean field approximation

    Li-Kang Yang🇨🇳 · Xiaofeng Luo🇨🇳 · Hong-Shi Zong🇨🇳

    We employ a new self-consistent mean field approximation of NJL model, which introduces a free parameter $\alpha$ ($\alpha$ reflects the weight of different interaction channels), to study the effects of the chiral chemical potential ${\mu }_5$ on QCD phase structure, especially the location of the QCD critical end point (CEP). We find that, at a high temperature, the critical temperature of QCD phase transition smoothly increases with ${\mu }_5$ at the beginning, and then decreases rapidly. At low temperature and high baryon density region, the increase of the chiral chemical potential will reduce the critical chemical potential of phase transition. The temperature of the CEP shows a non-monotonic dependence on the chiral chemical potential with a long plateau around the maximum. At ${\mu }_5=0$, we found that the CEP will disappear when the $\alpha$ value is larger than 0.71 and will reappear when the ${\mu }_5$ increases. This study is important for exploring the QCD phase structure and the location of CEP in chiral imbalanced systems.

    ↳ nucl-thhep-phPRD(2019)·28 citations
28. 28*

    Quasi-PDFs with twisted mass fermions

    Constantia Alexandrou🇨🇾 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Kyriakos Hadjiyiannakou🇨🇾 · Karl Jansen🇩🇪 · Aurora Scapellato🇵🇱 · Fernanda Steffens🇩🇪

    We discuss the recent progress in extracting partonic functions from the quasi-distribution approach, using twisted mass fermions. This concerns, among others, the investigation of several sources of systematic effects. Their careful analysis is a prerequisite to obtain precise determinations of PDFs from the lattice with realistic estimates of all uncertainties. In these proceedings, we shortly discuss systematic effects in the matching procedure. Moreover, we present preliminary results from our new simulations at the physical point. They involve, additionally, the dynamical strange and charm quarks, as well as a larger volume and a smaller lattice spacing than in our previous computations. In addition, we show first results from computations of generalized parton distributions (GPDs) in the quasi-distribution framework.

    ↳ hep-lathep-phPoS(2019)·18 citations
29. 29*

    Direct Detection Constraints on Dark Photons with CDEX-10 Experiment at the China Jinping Underground Laboratory

    Z. She🇨🇳 · L. P. Jia🇨🇳 · Q. Yue🇨🇳 · H. Ma🇨🇳 · K. J. Kang🇨🇳 · Y. J. Li🇨🇳 · M. Agartioglu🇹🇼 · H. P. An🇨🇳 · J. P. Chang🇨🇳 · J. H. Chen🇹🇼 · Y. H. Chen🇨🇳 · J. P. Cheng🇨🇳 and 72 other authors

    We report constraints on the dark photon effective kinetic mixing parameter ($\kappa$) with data taken from two $p$-type point-contact germanium detectors of the CDEX-10 experiment at the China Jinping Underground Laboratory. The 90\% confidence level upper limits on $\kappa$ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses ($m_V$) from 10 to 300 eV/$c^2$ in direct detection experiments. Considering dark photon as the cosmological dark matter, limits at 90\% confidence level with $m_V$ from 0.1 to 4.0 keV/$c^2$ are set from 449.6 kg-day data, with a minimum of $\kappa =1.3\times 10^{-15}$ at ${\mathrm{m}}_{\mathrm{V}}=200eV/{\mathrm{c}}^2$.

    ↳ hep-exhep-phphysics.ins-detPRL(2020)·49 citations
30. 30*

    Radiation reaction in electron-beam interactions with high-intensity lasers

    T. G. Blackburn🇸🇪

    Charged particles accelerated by electromagnetic fields emit radiation, which must, by the conservation of momentum, exert a recoil on the emitting particle. The force of this recoil, known as radiation reaction, strongly affects the dynamics of ultrarelativistic electrons in intense electromagnetic fields. Such environments are found astrophysically, e.g. in neutron star magnetospheres, and will be created in laser-matter experiments in the next generation of high-intensity laser facilities. In many of these scenarios, the energy of an individual photon of the radiation can be comparable to the energy of the emitting particle, which necessitates modelling not only of radiation reaction, but quantum radiation reaction. The worldwide development of multi-petawatt laser systems in large-scale facilities, and the expectation that they will create focussed electromagnetic fields with unprecedented intensities $>10^{23}\mathrm{W}{\text{cm}}^{-2}$, has motivated renewed interest in these effects. In this paper I review theoretical and experimental progress towards understanding radiation reaction, and quantum effects on the same, in high-intensity laser fields that are probed with ultrarelativistic electron beams. In particular, we will discuss how analytical and numerical methods give insight into new kinds of radiation-reaction-induced dynamics, as well as how the same physics can be explored in experiments at currently existing laser facilities.

    ↳ physics.plasm-phhep-phPlasma Phys.(2020)·99 citations
31. 31*

    Neutrino clustering in the Milky Way and beyond

    P. Mertsch🇩🇪 · G. Parimbelli🇮🇹 · P.F. de Salas🇸🇪 · S. Gariazzo🇪🇸 · J. Lesgourgues🇩🇪 · S. Pastor🇪🇸

    The standard cosmological model predicts the existence of a Cosmic Neutrino Background, which has not yet been observed directly. Some experiments aiming at its detection are currently under development, despite the tiny kinetic energy of the cosmological relic neutrinos, which makes this task incredibly challenging. Since massive neutrinos are attracted by the gravitational potential of our Galaxy, they can cluster locally. Neutrinos should be more abundant at the Earth position than at an average point in the Universe. This fact may enhance the expected event rate in any future experiment. Past calculations of the local neutrino clustering factor only considered a spherical distribution of matter in the Milky Way and neglected the influence of other nearby objects like the Virgo cluster, although recent $N$-body simulations suggest that the latter may actually be important. In this paper, we adopt a back-tracking technique, well established in the calculation of cosmic rays fluxes, to perform the first three-dimensional calculation of the number density of relic neutrinos at the Solar System, taking into account not only the matter composition of the Milky Way, but also the contribution of the Andromeda galaxy and the Virgo cluster. The effect of Virgo is indeed found to be relevant and to depend non-trivially on the value of the neutrino mass. Our results show that the local neutrino density is enhanced by 0.53% for a neutrino mass of 10 meV, 12% for 50 meV, 50% for 100 meV or 500% for 300 meV.

    ↳ astro-ph.COhep-phJCAP(2020)·51 citations
32. 32*

    Measurement of the $B_c^{-}$ meson production fraction and asymmetry in 7 and 13 TeV $pp$ collisions

    LHCb collaboration: R. Aaij · C. Abellán Beteta · T. Ackernley · B. Adeva · M. Adinolfi · H. Afsharnia · C.A. Aidala · S. Aiola · Z. Ajaltouni · S. Akar · P. Albicocco · J. Albrecht and 894 other authors

    The production fraction of the $B_c^{-}$ meson with respect to the sum of $B^{-}$ and ${\bar{B}}^0$ mesons is measured in both 7 and 13 TeV center-of-mass energy $pp$ collisions produced by the Large Hadron Collider (LHC), using the LHCb detector. The rate, approximately 3.7 per mille, does not change with energy, but shows a transverse momentum dependence. The $B_c^{-}-B_c^{+}$ production asymmetry is also measured, and is consistent with zero within the determined statistical and systematic uncertainties of a few percent.

    ↳ hep-exhep-phPRD(2019)·79 citations
33. 33*

    On-shell constructibility of Born amplitudes in spontaneously broken gauge theories

    Robert Franken🇩🇪 · Christian Schwinn🇩🇪

    We perform a comprehensive study of on-shell recursion relations for Born amplitudes in spontaneously broken gauge theories and identify the minimal shifts required to construct amplitudes with a given particle content and spin quantum numbers. We show that two-line or three-line shifts are sufficient to construct all amplitudes with five or more particles, apart from amplitudes involving longitudinal vector bosons or scalars, which may require at most five-line shifts. As an application, we revisit selection rules for multi-boson amplitudes using on-shell recursion and little-group transformations.

    ↳ hep-thhep-phJHEP(2020)·26 citations
34. 34*

    Spectroscopy of short-lived radioactive molecules: A sensitive laboratory for new physics

    R.F. Garcia Ruiz🇨🇭 · R. Berger🇩🇪 · J. Billowes🇬🇧 · C.L. Binnersley🇬🇧 · M.L. Bissell🇬🇧 · A.A. Breier🇩🇪 · A.J. Brinson🇺🇸 · K. Chrysalidis🇨🇭 · T. Cocolios🇧🇪 · B. Cooper🇬🇧 · K.T. Flanagan🇬🇧 · T.F. Giesen🇩🇪 and 15 other authors

    The study of molecular systems provides exceptional opportunities for the exploration of the fundamental laws of nature and for the search for physics beyond the Standard Model of particle physics. Measurements of molecules composed of naturally occurring nuclei have provided the most stringent upper bounds to the electron electric dipole moment to date, and offer a route to investigate the violation of fundamental symmetries with unprecedented sensitivity. Radioactive molecules - where one or more of their atoms possesses a radioactive nucleus - can contain heavy and deformed nuclei, offering superior sensitivity for EDM measurements as well as for other symmetry-violating effects. Radium monofluoride, RaF, is of particular interest as it is predicted to have an appropriate electronic structure for direct laser cooling. Furthermore, some Ra isotopes are known to be octupole deformed, thereby resulting in a large enhancement of their symmetry-violating nuclear moments. Until now,however, no experimental measurements of RaF have been performed, and their study is impeded by major experimental challenges, as no stable isotopes of radium exist. Here, we present a novel experimental approach to study short-lived radioactive molecules using the highly sensitive collinear resonance ionisation method. With this technique we have measured, for the first time, the energetically low-lying electronic states for each of the isotopically pure RaF molecules at the ISOLDE-CERN. Our results provide strong evidence of the existence of a suitable laser-cooling scheme for these molecules and constitute a pivotal step towards high-precision studies in these systems. Our findings open up new opportunities in the synthesis, manipulation and study of short-lived radioactive molecules, which will have a direct impact in many-body physics, astrophysics, nuclear structure, and fundamental physics research.

    ↳ nucl-thhep-phhep-thnucl-exNature(2020)·98 citations
35. 35*

    Equivalence of the phenomenological Tsallis distribution to the transverse momentum distribution of $q$-dual statistics

    A.S. Parvan🇷🇺

    In the present work, we have found that the phenomenological Tsallis distribution (which nowadays is largely used to describe the transverse momentum distributions of hadrons measured in $pp$ collisions at high energies) is consistent with the basis of the statistical mechanics if it belongs to the $q$-dual nonextensive statistics instead of the Tsallis one. We have defined the $q$-dual statistics based on the $q$-dual entropy which was obtained from the Tsallis entropy under the multiplicative transformation of the entropic parameter $q\to 1/q$. We have found that the phenomenological Tsallis distribution is equivalent to the transverse momentum distribution of the $q$-dual statistics in the zeroth term approximation. Since the $q$-dual statistics is properly defined, it provides a correct link between the phenomenological Tsallis distribution and the second law of thermodynamics.

    ↳ nucl-thhep-phEPJA(2020)·21 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.