Tue·Jun 18, 2019Tuesday·June 18, 2019

1. 01*

   Oscillons and Dark Matter

   Jan Olle🇪🇸 · Oriol Pujolas🇪🇸 · Fabrizio Rompineve🇪🇸

   Oscillons are bound states sustained by self-interactions that appear in rather generic scalar models. They can be extremely long-lived and in the context of cosmology they have a built-in formation mechanism - parametric resonance instability. These features suggest that oscillons can affect the standard picture of scalar ultra-light dark matter (ULDM) models. We explore this idea along two directions. First, we investigate numerically oscillon lifetimes and their dependence on the shape of the potential. We find that scalar potentials that occur in well motivated axion-like models can lead to oscillons that live up to $10^8$ cycles or more. Second, we discuss the observational constraints on the ULDM models once the presence of oscillons is taken into account. For a wide range of axion masses, oscillons decay around or after matter-radiation equality and can thus act as early seeds for structure formation. We also discuss the possibility that oscillons survive up to today. In this case they can most easily play the role of dark matter.

   hep-phastro-ph.COhep-thJCAP(2020)·75 citations
2. 02*

   Model Independent analysis of MeV scale dark matter: II. Implications from $e^{-}{e}^{+}$ colliders and Direct Detection

   Debajyoti Choudhury🇮🇳 · Divya Sachdeva🇮🇳

   Dark matter particles with masses in the sub-GeV range have escaped severe constraints from direct detection experiments such as LUX, PANDAX-II and XENON100 as the corresponding recoil energies are, largely, lower than the detector thresholds. In a companion paper, we demonstrated, in a model independent approach, that a significantly large fraction of the parameter space escapes the cosmological and astrophysical constraints. We show here, though, that the remaining parameter space lends itself to the possibility of discovery at both direct detection experiments (such as CRESST-II) as well as in a low-energy collider such as Belle-II.

   hep-phPRD(2019)·13 citations
3. 03*

   Constraining the $3-3-1$ model with heavy neutral leptons using $(g-2{)}_{\mu }$ and dark matter observables

   C. E. Alvarez-Salazar🇧🇷 · O. L. G. Peres🇧🇷

   We find constraints on the highest scale of symmetry breaking of a model with gauge symmetry $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X$ with heavy neutral leptons in the fermion triplets, calculating the anomalous magnetic moment of the muon and using results of the relic abundance of dark matter and experiments searching for its direct detection. In order to do this, we have calculated the one-loop contribution of new particles in the model to $(g-2{)}_{\mu }$, finding a favoured region for the scale at which $SU(3{)}_L$ is broken, and we have found lower bounds for this scale making a comparison of the predictions for the detection of a fermion dark matter candidate in the model in terms of simplified dark matter models, identifying the dominant portal for its interactions with standard model particles, and using constraints for the relic abundance and spin-independent scattering cross section of the fermion candidate with protons.

   hep-phPRD(2021)·10 citations
4. 04*

   Small $x$ phenomenology on gluon evolution through BFKL equation in light of a constraint in multi-Regge kinematics

   P. Phukan🇮🇳 · M. Lalune · J. K. Sarma🇮🇳

   We investigate the impact of so called kinematic constraint on gluon evolution at small $x$. Implanting the constraint on the real emission term of gluon ladder diagram, we obtain an integro-differential form of BFKL equation. Later we solve the equation analytically using the method of characteristics. We sketch the Bjorken x and transverse momentum $k_t^2$ dependence of our solution of unintegrated gluon distributions $f(x,k_t^2)$ in kinematic constraint supplemented BFKL equation and contrasted the same with original BFKL equation. Then we extract the collinear gluon density $xg(x,Q^2)$ from unintegrated gluon distributions $f(x,k_t^2)$ and compared our theoretical prediction with that of global data fits viz. NNPDF3.1sx and CT14. Finally we assess the sensitivity of $f(x,k_t^2)$ towards BFKL intercept $\lambda$ for three canonical choices of $\lambda$ viz. o.4, 0.5 and 0.6.

   hep-phCommun.Theor.Phys.(2020)·2 citations
5. 05*

   Contributions of Jets in Net Charge Fluctuations from the Beam Energy Scan at RHIC and LHC

   Bushra Ali🇮🇳 · Shaista Khan🇮🇳 · Shakeel Ahmad🇮🇳

   Dynamical net charge fluctuations have been studied in ultra-relativistic heavy-ion collisions from the beam energy scan at RHIC and LHC energies by carrying out the hadronic model simulation. Monte Carlo model, HIJING is used to generate events in two different modes, HIJING-default with jet quenching switched off and jet/minijet production switched off. A popular variable, ${\nu }_{[+-,dyn]}$ is used to study the net charge fluctuations in different centrality bins and the findings are compared with the available experimental values reported earlier. Although the broad features of net charge fluctuations are reproduced by the HIJING, yet the model predicts the larger magnitude of fluctuations as compared to the one observed in experiments. The role of jets/minijets production in reducing the net charge fluctuations is, however distinctly visible from the analysis of the two types of HIJING events. Furthermore, $d{N}_{ch}/d\eta$ and $1/N$ scaling is partially exhibited which is due to the fact that in HIJING, nucleus-nucleus collisions are treated as multiple independent nucleon-nucleon collisions.

   hep-phAdv.High Energy Phys.(2019)·0 citations
6. 06*

   R-Symmetric NMSSM

   Shuai Xu🇨🇳 · Sibo Zheng🇨🇳

   It is well known that the observed Higgs mass is more naturally explained in the NMSSM than in the MSSM. Without any violation of this success, there are variants on the NMSSM which can lead to new phenomenologies. In this study we propose a new variant of NMSSM by imposing an unbroken $R$ symmetry. We firstly identify the minimal structure of such scenario from the perspective of both simplicity and viability, then compare model predictions to current experimental limits, and finally highlight main features that differ from the well-known scenarios.

   hep-phhep-thCPC(2023)·0 citations
7. 07*

   Heavy hadron molecules in effective field theory: the emergence of exotic nuclear landscapes

   Manuel Pavon Valderrama🇨🇳

   Heavy hadron molecules were first theorized from a crude analogy with the deuteron and the nuclear forces binding it, a conjecture which was proven to be on the right track after the discovery of the $X(3872)$. However, this analogy with nuclear physics has not been seriously exploited beyond a few calculations in the two- and three-body sectors, leaving a great number of possible theoretical consequences unexplored. Here we show that nuclear and heavy hadron effective field theories are formally identical: using a suitable notation, there is no formal difference between these two effective field theories. For this, instead of using the standard heavy superfield notation, we have written the heavy hadron interactions directly in terms of the light quark degrees of freedom. We give a few examples of how to exploit this analogy, e.g. the calculation of the two-pion exchange diagrams. Yet the most relevant application of the present idea is the conjecture of exotic nuclear landscapes, i.e. the possibility of few heavy hadron bound states with characteristics similar to those of the standard nuclei.

   hep-phhep-latnucl-thEPJA(2020)·18 citations
8. 08*

   Top-quark pair production at the LHC: Fully differential QCD predictions at NNLO

   Stefano Catani🇮🇹 · Simone Devoto🇨🇭 · Massimiliano Grazzini🇨🇭 · Stefan Kallweit🇮🇹 · Javier Mazzitelli🇨🇭

   We report on a new fully differential calculation of the next-to-next-to-leading-order (NNLO) QCD radiative corrections to the production of top-quark pairs at hadron colliders. The calculation is performed by using the $q_T$ subtraction formalism to handle and cancel infrared singularities in real and virtual contributions. The computation is implemented in the Matrix framework, thereby allowing us to efficiently compute arbitrary infrared-safe observables for stable top quarks. We present NNLO predictions for several single- and double-differential kinematical distributions in $pp$ collisions at the centre-of-mass energy $\sqrt{s}=13$ TeV, and we compare them with recent LHC data by the CMS collaboration.

   hep-phhep-exJHEP(2019)·213 citations
9. 09*

   Improved description of the HERA data with a new simple PDF parametrization

   Francesco Giuli🇮🇹 · Marco Bonvini🇮🇹

   A new parametrization for the parton distribution functions with a higher flexibility in the small-$x$ region is presented. It has been implemented in the xFitter open-source PDF fitting tool, and compared to the default xFitter parametrization, used for the determination of the HERAPDF set. It has been found that the combined inclusive HERA I+II data can be described using NNLO theory with a significantly higher quality than HERAPDF2.0: the ${\chi }^2$ is reduced by more than 60 units, having used only four more parameters. Our result highlights a significant parametrization bias in the default xFitter parametrization at small $x$, which would lead to even more dramatic effects when used for higher energy colliders, where the small-$x$ region is more relevant. We also find that the inclusion of small-$x$ resummation leads to a further reduction by approximately 30 extra units in ${\chi }^2$. In this contribution, we review the results of the recent paper "A new simple PDF parametrization: improved description of the HERA data" (arXiv:1902.11125).

   hep-phhep-exPoS(2019)·1 citation
10. 10*

    The decays $\tau \to (K,K(1460)){\nu }_{\tau }$ and the value of the weak decay coefficients $F_K$ and $F_{K^{{}^{\prime }}}$ in the extended NJL model

    M. K. Volkov🇷🇺 · K. Nurlan🇷🇺 · A . A. Pivovarov🇷🇺

    In the extended NJL model, the decay widths of $\tau \to (K,K(1460)){\nu }_{\tau }$, $(K,K(1460))\to \mu {\nu }_{\mu }$ are calculated. The contributions from intermediate axial-vector mesons $K_1(1270)$, $K_1(1400)$ and the first radially excited state $K_1(1650)$ are taken into account. Estimates for the weak decay coefficients $F_K$ and $F_{K^{{}^{\prime }}}$ are given. Predictions are made for the width of $\tau \to K(1460){\nu }_{\tau }$ decay and $F_{K^{{}^{\prime }}}$ constant.

    hep-phInt.J.Mod.Phys.A(2019)·12 citations
11. 11*

    Sudakov suppression of the Balitsky-Kovchegov kernel

    Du-xin Zheng🇨🇳 · Jian Zhou🇨🇳

    To sum high energy leading logarithms in a consistent way, one has to impose the strong ordering in both projectile rapidity and dense target rapidity simultaneously, which results in a kinematically improved Balitsky-Kovchegov(BK) equation. We find that beyond this strong ordering region, the important sub-leading double logarithms arise at high order due to the incomplete cancellation between real corrections and virtual corrections in a t-channel calculation. Based on this observation, we further argue that these double logarithms are the Sudakov type ones, and thus can be resummed into an exponential leading to a Sudakov suppressed BK equation.

    hep-phJHEP(2019)·22 citations
12. 12*

    The cos${\varphi }_R$ asymmetry of dihadron production in double longitudinally polarized SIDIS

    Wei Yang🇨🇳 · Hui Li🇨🇳 · Zhun Lu🇨🇳

    We present a study on the double longitudinal-spin asymmetry of dihadron production in semi-inclusive deep inelastic scattering, in which the total transverse momentum of the final-state hadron pairs is integrated out. In particular, we investigate the origin of the $\cos {\varphi }_R$ azimuthal asymmetry for which we take into account the coupling of the helicity distribution $g_1$ and the twist-3 dihadron fragmentation function ${\tilde{D}}^{\sphericalangle }$. We calculate the $s$-wave and $p$-wave interference term ${\tilde{D}}_{ot}^{\sphericalangle }$ in a spectator model. We estimate the $\cos {\varphi }_R$ asymmetry at the kinematics of COMPASS which is collecting data on dihadron production in polarized deep inelastic scattering. The prediction of the same asymmetry at JLab 12GeV and a future EIC are also presented. Our study indicates that measuring the $\cos {\varphi }_R$ asymmetry in SIDIS may be a ideal way to probe the dihadron fragmentation function ${\tilde{D}}^{\sphericalangle }$.

    hep-phhep-exPRD(2019)·1 citation
13. 13*

    Role of Future Lepton Colliders for Fermionic Z-portal Dark Matter

    Dilip Kumar Ghosh🇮🇳 · Taisuke Katayose🇯🇵 · Shigeki Matsumoto🇯🇵 · Ipsita Saha🇯🇵 · Satoshi Shirai🇯🇵 · Tomohiko Tanabe🇯🇵

    The fermionic Z-portal dark matter model suffers from severe constraints from direct detection experiments. However, a narrow parameter space around the Z-funnel region is beyond the reach due to the resonance annihilation. In this paper, we provide an intriguing collider prospect for probing the Z-funnel dark matter mass range at the future lepton colliders including the beam polarization feature. We have done a comprehensive analysis for mono-photon signal at the colliders for such a dark matter. A realistic estimation for the 90% C.L. constraints with the systematic beam uncertainties has also been provided.

    hep-phhep-exPRD(2020)·5 citations
14. 14*

    Inflation, Proton Decay, and Higgs-Portal Dark Matter in $SO(10)\times U(1{)}_{\psi }$

    Nobuchika Okada🇺🇸 · Digesh Raut🇺🇸 · Qaisar Shafi🇺🇸

    We propose a simple non-supersymmetric grand unified theory (GUT) based on the gauge group $SO(10)\times U(1{)}_{\psi }$. The model includes 3 generations of fermions in $16$ ($+1$), $10$ ($-2$) and $1$ ($+4$) representations. The $16$-plets contain Standard Model (SM) fermions plus right-handed neutrinos, and the $10$-plet and the singlet fermions are introduced to make the model anomaly-free. Gauge coupling unification at $M_{GUT}\simeq 5\times 10^{15}-10^{16}$ GeV is achieved by including an intermediate Pati-Salam breaking at $M_I\simeq 10^{12}-10^{11}$ GeV, which is a natural scale for the seesaw mechanism. For $M_I\simeq 10^{12}-10^{11}$, proton decay will be tested by the Hyper-Kamiokande experiment. The extra fermions acquire their masses from $U(1{)}_{\psi }$ symmetry breaking, and a $U(1{)}_{\psi }$ Higgs field drives a successful inflection-point inflation with a low Hubble parameter during inflation, $H_{inf}\ll M_I$. Hence, cosmologically dangerous monopoles produced from $SO(10)$ and PS breakings are diluted away. The reheating temperature after inflation can be high enough for successful leptogenesis. With the Higgs field contents of our model, a ${\mathbf{Z}}_2$ symmetry remains unbroken after GUT symmetry breaking, and the lightest mass eigenstate among linear combinations of the $10$-plet and the singlet fermions serves as a Higgs-portal dark matter (DM). We identify the parameter regions to reproduce the observed DM relic density while satisfying the current constraint from the direct DM detection experiments. The present allowed region will be fully covered by the future direct detection experiments such as LUX-ZEPLIN DM experiment. In the presence of the extra fermions, the SM Higgs potential is stabilized up to $M_I$.

    hep-phastro-ph.COhep-thEPJC(2019)·10 citations
15. 15*

    Lorentz Invariance Violation effects on UHECR propagation: a geometrized approach

    M.D.C. Torri🇮🇹 · S. Bertini🇮🇹 · M. Giammarchi🇮🇹 · L. Miramonti🇮🇹

    We explore the possibility to geometrize the interaction of massive fermions with the quantum structure of space-time, trying to create a theoretical background, in order to explain what some recent experimental results seem to implicate on the propagation of Ultra High Energy Cosmic Rays (UHECR). We will investigate part of the phenomenological implications of this approach on the predicted effect of the UHECR suppression, in fact recent evidences seem to involve the modification of the GZK cut-off phenomenon. The search for an effective theory, which can explain this physical effect, is based on Lorentz Invariance Violation (LIV), which is introduced via Modified Dispersion Relations (MDRs). Furthermore we illustrate that this perspective implies a more general geometry of space-time than the usual Riemannian one, indicating, for example, the opportunity to resort to Finsler theory.

    hep-phJHEAp(2018)·17 citations
16. 16*

    The Higgs width in the SMEFT

    Ilaria Brivio🇩🇰 · Tyler Corbett🇩🇰 · Michael Trott🇩🇰

    We calculate the total and partial inclusive Higgs widths at leading order in the Standard Model Effective Field Theory (SMEFT). We report results incorporating SMEFT corrections for two and four body Higgs decays through vector currents in this limit. The narrow width approximation is avoided and all phase space integrals are directly evaluated. We explain why the narrow width approximation fails more significantly in the SMEFT compared to the SM, despite the narrowness of the observed $\mathrm{SU}(2)\times \mathrm{U}(1)$ bosons in both theories. Our results are presented in a manner that allows various input parameter schemes to be used, and they allow the inclusive branching ratios and decay widths of the Higgs to be numerically determined without a Monte Carlo generation of phase space for each Wilson coefficient value chosen.

    hep-phhep-exJHEP(2019)·62 citations
17. 17*

    Double D-meson production in proton-proton and proton-lead collisions at the LHC

    Ilkka Helenius🇫🇮 · Hannu Paukkunen🇫🇮

    We consider the simultaneous production of two heavy-flavoured hadrons - particularly D mesons - at the LHC. We base our calculations on collinearly factorized QCD at next-to-leading order, using the contemporary parton distribution functions and D-meson fragmentation functions. The contributions of double-parton scatterings are included in the approximation of independent partonic interactions. Our framework benchmarks well with the available proton-proton data from the LHCb collaboration giving us confidence to make predictions for proton-lead collisions. Our results indicate that the double D-meson production in proton-lead collisions should be measurable at the LHCb kinematics with the already collected Run-II data, and should provide evidence for double-parton scattering at perturbative scales with a nuclear target.

    hep-phPLB(2020)·23 citations
18. 18*

    Azimuthal asymmetries in unpolarized SIDIS and Drell-Yan processes: a case study towards TMD factorization at subleading twist

    Alessandro Bacchetta🇮🇹 · Giuseppe Bozzi🇮🇹 · Miguel G. Echevarria🇮🇹 · Cristian Pisano🇮🇹 · Alexey Prokudin🇺🇸 · Marco Radici🇮🇹

    We consider the azimuthal distribution of the final observed hadron in semi-inclusive deep-inelastic scattering and the lepton pair in the Drell-Yan process. In particular, we focus on the $\cos \varphi$ modulation of the unpolarized cross section and on its dependence upon transverse momentum. At low transverse momentum, for these observables we propose a factorized expression based on tree-level approach and conjecture that the same formula is valid in transverse-momentum dependent (TMD) factorization when written in terms of subtracted TMD parton distributions. Our formula correctly matches with the collinear factorization results at high transverse momentum, solves a long-standing problem and is a necessary step towards the extension of the TMD factorization theorems up to the subleading twist.

    hep-phPLB(2019)·44 citations
19. 19*

    Weak production of strange $\Xi$ baryons off the nucleon

    M. Rafi Alam🇮🇳 · I. Ruiz Simo🇪🇸

    The charged current Cabibbo-supressed associated $K\Xi$ production off the nucleon induced by anti-neutrinos is studied at low and intermediate energies. The non-resonant terms are obtained using a microscopical model based on the SU(3) chiral Lagrangian. The basic parameters of the model are $f_{\pi }$, the pion decay constant, Cabibbo's angle, the proton and neutron magnetic moments and the axial vector coupling constants for the baryons octet, D and F, that are obtained from the analysis of the semileptonic decays of neutron and hyperons. In addition, we also consider ${\Sigma }^{\ast }(1385)$ resonance, which can decay in $K\Xi$ final state when this channel is open. The studied mechanism is the prime source of $\Xi$ production at anti-neutrino energies around $2$ GeV and the calculated cross sections at these energies can be measured at the current and future neutrino experiments.

    hep-phhep-exnucl-thPRD(2019)·3 citations
20. 20*

    Probing New Physics with $\bar{B}\to \rho (770){\ell }^{-}{\bar{\nu }}_{\ell }$ and $\bar{B}\to a_1(1260){\ell }^{-}{\bar{\nu }}_{\ell }$

    P. Colangelo🇮🇹 · F. De Fazio🇮🇹 · F. Loparco🇮🇹

    The $B$ meson semileptonic modes to $\rho (770)$ and $a_1(1260)$ are useful to pin down possible non Standard Model effects. The 4d differential $\bar{B}\to \rho (\pi \pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ and $\bar{B}\to a_1(\rho \pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ decay distributions are computed in SM and in extensions involving new Lepton Flavour Universality violating semileptonic $b\to u$ operators. The Large Energy limit for the light meson is also considered for both modes. The new effective couplings are constrained using the available data, and several observables in $\bar{B}\to \rho (\pi \pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ in which NP effects can be better identified are selected, using the angular coefficient functions. The complementary role of $\bar{B}\to \rho (\pi \pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ and $\bar{B}\to a_1(\rho \pi ){\ell }^{-}{\bar{\nu }}_{\ell }$ is discussed.

    hep-phhep-exhep-latPRD(2019)·39 citations
21. 21*

    Exotic Spin-Dependent Interaction Searches at Indiana University

    I. Lee · J. Shortino · J. Biermen · A. Din · A. Grossman · M. Gabel · E. Guess · C.-Y. Liu · J.C. Long · S. Reger · A. Reid · M. Severinov and 5 other authors

    The axion is a hypothesized particle appearing in various theories beyond the Standard Model. It is a light spin-0 boson initially postulated to solve the strong CP problem and is also a strong candidate for dark matter. If the axion or an axion-like particle exists, it would mediate a P-odd and T-odd spin-dependent interaction. We describe two experiments under development at Indiana University-Bloomington to search for such an interaction.

    hep-ph0 citations
22. 22*

    Are there any challenges in the charmonia production and polarization at the LHC?

    S.P. Baranov🇷🇺 · A.V. Lipatov🇷🇺

    We analyze the inclusive prompt production of ${\psi }^{\prime }$, ${\chi }_c$, $J/\psi$ and ${\eta }_c$ mesons at the LHC using the $k_T$-factorization approach. Our consideration is based on the off-shell production amplitudes for hard partonic subprocesses, nonrelativistic QCD formalism for the formation of bound states and transverse momentum dependent (or unintegrated) gluon densities in a proton derived from Catani-Ciafaloni-Fiorani-Marchesini equation. The nonperturbative color octet transitions are treated in terms of the multipole radiation theory. We extract the corresponding long-distance matrix elements from a combined fit to transverse momentum distributions measured at various LHC experiments. We make predictions for the polarization parameters ${\lambda }_{\theta }$, ${\lambda }_{\varphi }$, ${\lambda }_{\theta \varphi }$ and the frame-independent parameter ${\lambda }^{\ast }$ and compare them to the available ${\psi }^{\prime }$ and $J/\psi$ data. Finally, we present a universal set of parameters that provides a reasonable simultaneous description for the whole body of the LHC data (on the $p_T$ distributions, relative production rates and polarization observables) for the whole charmonium family.

    hep-phPRD(2019)·39 citations
23. 23*

    Jet fragmentation functions for $Z$-tagged jets

    Zhong-Bo Kang🇺🇸 · Kyle Lee🇺🇸 · John Terry🇺🇸 · Hongxi Xing🇨🇳

    Recently the LHCb collaboration has measured both longitudinal and transverse momentum distribution of hadrons produced inside $Z$-tagged jets in proton-proton collisions at the Large Hadron Collider. These distributions are commonly referred to as jet fragmentation functions and are characterized by the longitudinal momentum fraction $z_h$ of the jet carried by the hadron and the transverse momentum $j_{\perp }$ with respect to the jet direction. We derive a QCD formalism within Soft-Collinear Effective Theory to describe these distributions and find that the $z_h$-dependence provides information on standard collinear fragmentation functions, while $j_{\perp }$-dependence probes transverse momentum dependent (TMD) fragmentation functions. We perform theoretical calculations and compare our results with the LHCb data. We find good agreement for the intermediate $z_h$ region. For $j_{\perp }$-dependence, we suggest binning in both $z_h$ and $j_{\perp }$, which would lead to a more direct probing of TMD fragmentation functions.

    hep-phhep-exnucl-thPLB(2019)·36 citations
24. 24*

    Interpretable deep learning for nuclear deformation in heavy ion collisions

    Long-Gang Pang🇺🇸 · Kai Zhou🇩🇪 · Xin-Nian Wang🇨🇳

    The structure of heavy nuclei is difficult to disentangle in high-energy heavy-ion collisions. The deep convolution neural network (DCNN) might be helpful in mapping the complex final states of heavy-ion collisions to the nuclear structure in the initial state. Using DCNN for supervised regression, we successfully extracted the magnitude of the nuclear deformation from event-by-event correlation between the momentum anisotropy or elliptic flow ($v_2$) and total number of charged hadrons ($d{N}_{\mathrm{ch}}/d\eta$) within a Monte Carlo model. Furthermore, a degeneracy is found in the correlation between collisions of prolate-prolate and oblate-oblate nuclei. Using the Regression Attention Mask algorithm which is designed to interpret what has been learned by DCNN, we discovered that the correlation in total-overlapped collisions is sensitive to only large nuclear deformation, while the correlation in semi-overlapped collisions is discriminative for all magnitudes of nuclear deformation. The method developed in this study can pave a way for exploration of other aspects of nuclear structure in heavy-ion collisions.

    ↳ nucl-thhep-ph23 citations
25. 25*

    A machine learning study to identify spinodal clumping in high energy nuclear collisions

    Jan Steinheimer🇩🇪 · LongGang Pang🇺🇸 · Kai Zhou🇩🇪 · Volker Koch🇺🇸 · Jørgen Randrup🇺🇸 · Horst Stoecker🇩🇪

    The coordinate and momentum space configurations of the net baryon number in heavy ion collisions that undergo spinodal decomposition, due to a first-order phase transition, are investigated using state-of-the-art machine-learning methods. Coordinate space clumping, which appears in the spinodal decomposition, leaves strong characteristic imprints on the spatial net density distribution in nearly every event which can be detected by modern machine learning techniques. On the other hand, the corresponding features in the momentum distributions cannot clearly be detected, by the same machine learning methods, in individual events. Only a small subset of events can be systematically differentiated if only the momentum space information is available. This is due to the strong similarity of the two event classes, with and without spinodal decomposition. In such scenarios, conventional event-averaged observables like the baryon number cumulants signal a spinodal non-equilibrium phase transition. Indeed the third-order cumulant, the skewness, does exhibit a peak at the beam energy (${\mathrm{E}}_{\mathrm{lab}}=3-4$ A GeV), where the transient hot and dense system created in the heavy ion collision reaches the first-order phase transition.

    ↳ nucl-thhep-phJHEP(2019)·65 citations
26. 26*

    Detecting new signals under background mismodelling

    Sara Algeri🇺🇸

    Searches for new astrophysical phenomena often involve several sources of non-random uncertainties which can lead to highly misleading results. Among these, model-uncertainty arising from background mismodelling can dramatically compromise the sensitivity of the experiment under study. Specifically, overestimating the background distribution in the signal region increases the chances of missing new physics. Conversely, underestimating the background outside the signal region leads to an artificially enhanced sensitivity and a higher likelihood of claiming false discoveries. The aim of this work is to provide a unified statistical strategy to perform modelling, estimation, inference, and signal characterization under background mismodelling. The method proposed allows to incorporate the (partial) scientific knowledge available on the background distribution and provides a data-updated version of it in a purely nonparametric fashion without requiring the specification of prior distributions on the parameters. Applications in the context of dark matter searches and radio surveys show how the tools presented in this article can be used to incorporate non-stochastic uncertainty due to instrumental noise and to overcome violations of classical distributional assumptions in stacking experiments.

    ↳ physics.data-anastro-ph.HEastro-ph.IMhep-ph+1PRD(2020)·8 citations
27. 27*

    Dynamically Generated Inflation from Non-Riemannian Volume Forms

    David Benisty🇮🇱 · Eduardo Guendelman🇮🇱 · Emil Nissimov🇧🇬 · Svetlana Pacheva🇧🇬

    We propose a simple modified gravity model without any initial matter fields in terms of several alternative non-Riemannian spacetime volume elements within the metric (second order) formalism. We show how the non-Riemannian volume-elements, when passing to the physical Einstein frame, create a canonical scalar field and produce dynamically a non-trivial inflationary-type potential for the latter with a large flat region and a stable low-lying minimum. We study the evolution of the cosmological solutions from the point of view of theory of dynamical systems. The theory predicts the spectral index $n_s\approx 0.96$ and the tensor-to-scalar ratio $r\approx 0.002$ for 60 e-folds, which is in accordance with the observational data. In the future Euclid and SPHEREx missions or the BICEP3 experiment are expected to provide experimental evidence to test those predictions.

    ↳ gr-qchep-phhep-thEPJC(2019)·16 citations
28. 28*

    Presupernova neutrino signals as potential probes of neutrino mass hierarchy

    Gang Guo🇩🇪 · Yong-Zhong Qian🇺🇸 · Alexander Heger🇦🇺

    We assess the potential of using presupernova neutrino signals at the Jiangmen Underground Neutrino Observatory (JUNO) to probe the yet-unknown neutrino mass hierarchy. Using models for stars of 12, 15, 20, and 25 solar masses, we find that if the electron antineutrino signals from such a star can be predicted precisely and the star is within ~440-880 pc, the number of events of electron antineutrino captures on protons detected within one day of its explosion allows to determine the hierarchy at the > ~95% confidence level. For determination at this level using such signals from Betelgeuse, which is at a distance of ~222 pc, the uncertainty in the predicted number of signals needs to be < ~14-30%. In view of more realistic uncertainties, we discuss and advocate a model-independent determination using both electron neutrino and antineutrino signals from Betelgeuse. This method is feasible if the cosmogenic background for neutrino-electron scattering events can be reduced by a factor of ~2.5-10 from the current estimate. Such reduction might be achieved by using coincidence of the background events, the exploration of which for JUNO is highly desirable.

    ↳ astro-ph.HEhep-phnucl-thPLB(2019)·14 citations
29. 29*

    Study of Lepton Universality at Belle

    Markus Tobias Prim🇩🇪

    The Belle Collaboration presented three recent Belle analyses: The search for $B\to l\nu \gamma$ ($l=e,\mu$) with improved hadronic tagging, the search for $B\to \mu {\nu }_{\mu }$ with inclusive tagging and the test of lepton universality in $B\to K^{\ast }ll$ ($l=e,\mu$) decays.

    ↳ hep-exhep-ph7 citations
30. 30*

    Supersymmetry, Ricci Flat Manifolds and the String Landscape

    Bobby Samir Acharya🇬🇧

    A longstanding question in superstring/$M$ theory is does it predict supersymmetry below the string scale? We formulate and discuss a necessary condition for this to be true; this is the mathematical conjecture that all stable, compact Ricci flat manifolds have special holonomy in dimensions below eleven. Almost equivalent is the proposal that the landscape of all geometric, stable, string/$M$ theory compactifications to Minkowski spacetime (at leading order) are supersymmetric. For simply connected manifolds, we collect together a number of physically relevant mathematical results, emphasising some key outstanding problems and perhaps less well known results. For non-simply connected, non-supersymmetric Ricci flat manifolds we demonstrate that many cases suffer from generalised Witten bubble of nothing instabilities.

    ↳ hep-thgr-qchep-phmath.DGJHEP(2020)·46 citations
31. 31*

    AMS-02 antiprotons' consistency with a secondary astrophysical origin

    Mathieu Boudaud🇫🇷 · Yoann Génolini🇧🇪 · Laurent Derome🇫🇷 · Julien Lavalle🇫🇷 · David Maurin🇫🇷 · Pierre Salati🇫🇷 · Pasquale D. Serpico🇫🇷

    The AMS-02 experiment has ushered cosmic-ray physics into precision era. In a companion paper, we designed an improved method to calibrate propagation models on B/C data. Here we provide a robust prediction of the $\bar{p}$ flux, accounting for several sources of uncertainties and their correlations. Combined with a correlation matrix for the $\bar{p}$ data, we show that the latter are consistent with a secondary origin. This paper presents key elements relevant to the dark matter search in this channel, notably by pointing out the inherent difficulties in achieving predictions at the percent-level precision.

    ↳ astro-ph.HEhep-phPRResearch(2020)·122 citations
32. 32*

    Non-Gaussian Formation of Primordial Black Holes: Effects on the Threshold

    Alex Kehagias🇬🇷 · Ilia Musco🇪🇸 · Antonio Riotto🇨🇭

    Primordial black holes could have been formed in the early universe from sufficiently large cosmological perturbations re-entering the horizon when the Universe is still radiation dominated. These originate from the spectrum of curvature perturbations generated during inflation at small-scales. Because of the non-linear relation between the curvature perturbation $\zeta$ and the overdensity $\delta \rho$, the formation of the primordial black holes is affected by intrinsic non-Gaussianity even though the curvature perturbation is Gaussian. We investigate the impact of this non-Gaussianity on the critical threshold ${\delta }_c$ which measures the excess of mass of the perturbation, finding a relative change with respect to the value obtained using a linear relation between $\zeta$ and $\delta \rho$, of a few percent. This shows that the value of the critical threshold is rather robust against non-linearities. The same holds also when cosmologically interesting values of local primordial non-Gaussianity are added to the curvature perturbation.

    ↳ astro-ph.COgr-qchep-phJCAP(2019)·102 citations
33. 33*

    Renormalons in quantum mechanics

    Cihan Pazarbasi🇹🇷 · Dieter Van den Bleeken🇹🇷

    We present a nonrelativistic one-particle quantum mechanics whose perturbative S-matrix exhibits a renormalon divergence that we explicitely compute. The potential of our model is the sum of the 2d Dirac $\delta$-potential -- known to require renormalization -- and a 1d Dirac $\delta$-potential tilted at an angle. We argue that renormalons are not specific to this example and exist for a much wider class of potentials. The ambiguity in the Borel summation of the perturbative series due to the renormalon pole is resolved by the physical condition of causality through careful consideration of the $iϵ$ prescription. The suitably summed perturbative result coincides with the exact answer obtained through the operator formalism for scattering.

    ↳ hep-thhep-phJHEP(2019)·16 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.