Thu·Nov 29, 2018Thursday·November 29, 2018

1. 01*

   Seeing Higher-Dimensional Grand Unification In Primordial Non-Gaussianities

   Soubhik Kumar🇺🇸 · Raman Sundrum🇺🇸

   The observed low-energy values of the $SU(3)\times SU(2)\times U(1)$ gauge couplings, extrapolated via the minimal Standard Model Renormalization Group evolution, hint at the exciting possibility of a Grand Unified Theory (GUT) at $M_U\sim 10^{14}$ GeV --- a scale, however, too high to probe directly via collider searches. Fortunately, since the Hubble scale H can be as high as $5\times 10^{13}$ GeV $\sim M_U$ during the inflationary era, such GUT scale states can be cosmologically produced at that time and leave direct on-shell signatures such as their masses and spins, via primordial non-Gaussianity (NG). We explore this possibility in one of its simplest realizations given by the extra-dimensional framework of orbifold GUTs, in which proton decay can be straightforwardly suppressed to be within the stringent bounds. Here, along with the massive GUT states there must also be H-mass spin-2 Kaluza-Klein (KK) gravitons, collectively giving rise to striking NG signatures. In our set-up we localize the inflaton on one of the boundaries of an extra dimension. The inflationary vacuum energy can readily lead to formation of a horizon in the bulk, where the KK modes then form a continuum above a mass gap of $\sim \mathcal{O}(H)$. We find that the optimal case for observable NG signals is when the extra dimension is stabilized close to the onset of this horizon, ensuring a discrete KK spectrum such that the lightest KK modes can be cosmologically produced without significant Boltzmann suppressions. Although we mostly focus on the case where there is no higher-dimensional cosmological constant, we also obtain considerable holographic insights from the ${\text{AdS}}_5/{\text{CFT}}_4$ correspondence when such a cosmological constant is included.

   hep-phastro-ph.COgr-qcJHEP(2019)·93 citations
2. 02*

   Mixed QCD-electroweak corrections to Higgs production via gluon fusion in the small mass approximation

   Charalampos Anastasiou🇨🇭 · Vittorio Del Duca🇨🇭 · Elisabetta Furlan🇨🇭 · Bernhard Mistlberger🇺🇸 · Francesco Moriello🇨🇭 · Armin Schweitzer🇨🇭 · Caterina Specchia🇨🇭

   We compute the mixed QCD-electroweak corrections to the cross section for the production of a Higgs boson via gluon fusion, in the limit of a small mass of the electroweak gauge bosons. This limit is regular and we calculate it by setting the W, Z masses to zero in the Feynman rules for their propagators. Our analytic results provide an independent check, in a non-trivial limit, of a recent exact computation for the three-loop mixed QCD and electroweak virtual corrections and the corresponding contribution to the cross section in the soft-virtual approximation. From our calculation in the small mass approximation, we can infer the second term in the expansion of the cross section around the threshold limit with its exact dependence on the masses of the W, Z bosons. Furthermore we find that in the small mass approximation the non-factorizable contributions from the real radiation, so far unknown for full gauge boson mass dependence, are modest in comparison to the known factorizable and virtual contributions to the full $\mathcal{O}({\alpha }_s^3{\alpha }^2)$ mixed QCD and electroweak cross-section. This furnishes a new phenomenological test of estimates for the mixed QCD and electroweak corrections, which were based on the hypothesis of factorization of QCD and electroweak corrections.

   hep-phJHEP(2019)·28 citations
3. 03*

   Three-component multiplicity distribution, oscillation of combinants and properties of clans in $pp$ collisions at the LHC

   I. Zborovský🇨🇿

   Multiplicity distributions of charged particles measured by the ATLAS Collaboration in proton-proton collisions at $\sqrt{s}=8$ and 13 TeV are analyzed in the framework of a weighted superposition of three negative binomial distribution functions. The examination of the experimental data confirms the existence of a narrow peak at low multiplicities found earlier at $\sqrt{s}=0.9$ and 7 TeV. The peak is described by the third separate component of the total distribution. The energy dependence of the multiplicity characteristics of the three-component scenario is studied. It is demonstrated that the third multiplicity component might be responsible for oscillations of combinants observed lately in the analysis of the multiplicity distributions measured in proton-proton collisions at the LHC. Some consequences of the three-component description of the data for the clan parameters are analyzed.

   hep-phEPJC(2018)·26 citations
4. 04*

   Theory Vision talk at LHCP2018

   Gavin P. Salam🇨🇭

   Particle physics is sometimes described as going through a crisis, notably because of the continued lack of discovery of physics beyond the Standard Model, despite the LHC having operated at close to maximal energy for some years now. Here, I argue that we should not underestimate the significance of recent progress and future prospects in the Higgs sector of the Standard Model. This is especially the case for the Yukawa interactions and the structure of the Higgs potential, both of which are unlike any sector that has been established and stress-tested before in particle physics. Other topics that I touch on include the still substantial scope for increasing the reach of searches at LHC, the increasing role of precision in hadron-collider physics and the rich interplay that is developing between heavy-ion and proton-proton physics.

   hep-phhep-exPoS(2018)·6 citations
5. 05*

   Search for neutral Higgs bosons within Type-I 2HDM at future linear colliders

   Majid Hashemi🇮🇷 · Gholamhossein Haghighat (Physics Department, College of Sciences, Shiraz University, Shiraz, Iran)🇮🇷

   In this study, we investigate observability of the neutral scalar ($H$) and pseudoscalar ($A$) Higgs bosons in the framework of the Type-I 2HDM at SM-like scenario at a linear collider operating at $\sqrt{s}=$ 500 and 1000 GeV. The signal process chain $e^{-}{e}^{+}\to AH\to ZHH\to jjb\bar{b}b\bar{b}$ where $jj$ is a di-jet resulting from the $Z$ boson decay and $b\bar{b}$ is a $b$ quark pair, is assumed and several benchmark scenarios with different mass hypotheses are studied. The assumed signal process is mainly motivated by the possible enhancements the decay modes $A\to ZH$ and $H\to b\bar{b}$ may receive in the Type-I. Event generation is performed for the assumed scenarios separately and the beamstrahlung effects are taken into account. The detector response is simulated based on the SiD detector at the ILC and the simulated events are analyzed to obtain candidate mass distributions of the Higgs bosons. According to the results, the top quark pair production process has the most contribution to the total background and is, however, well-controlled. Results indicate that, in all of the considered scenarios, both of the Higgs bosons $H$ and $A$ are observable with signals exceeding $5\sigma$ with possibility of mass measurement. To be specific, at $\sqrt{s}=500$ GeV, the region of parameter space with $m_H=150$ GeV and $200\le m_A\le 250$ GeV is observable at the integrated luminosity of 500 $f{b}^{-1}$. Also, at $\sqrt{s}=1000$ GeV, the region with $150\le m_H\le 250$ GeV and $200\le m_A\le 330$ GeV with a mass splitting of 50-100 GeV between the $H$ and $A$ Higgs bosons is observable at the same integrated luminosity.

   hep-phEPJC(2019)·9 citations
6. 06*

   LHC Constraints on a $B-L$ Gauge Model using Contur

   S. Amrith🇬🇧 · J. M. Butterworth🇬🇧 · F. F. Deppisch🇬🇧 · W. Liu🇬🇧 · A. Varma🇬🇧 · D. Yallup🇬🇧

   The large and growing library of measurements from the Large Hadron Collider has significant power to constrain extensions of the Standard Model. We consider such constraints on a well-motivated model involving a gauged and spontaneously-broken $B-L$ symmetry, within the Contur framework. The model contains an extra Higgs boson, a gauge boson, and right-handed neutrinos with Majorana masses. This new particle content implies a varied phenomenology highly dependent on the parameters of the model, very well-suited to a general study of this kind. We find that existing LHC measurements significantly constrain the model in interesting regions of parameter space. Other regions remain open, some of which are within reach of future LHC data.

   hep-phhep-exJHEP(2019)·77 citations
7. 07*

   Analytic helicity amplitudes for two-loop five-gluon scattering: the single-minus case

   Simon Badger🇬🇧 · Christian Brønnum-Hansen🇬🇧 · Heribertus Bayu Hartanto🇬🇧 · Tiziano Peraro🇨🇭

   We present a compact analytic expression for the leading colour two-loop five-gluon amplitude in Yang-Mills theory with a single negative helicity and four positive helicities. The analytic result is reconstructed from numerical evaluations over finite fields. The numerical method combines integrand reduction, integration-by-parts identities and Laurent expansion into a basis of pentagon functions to compute the coefficients directly from six-dimensional generalised unitarity cuts.

   hep-phhep-thJHEP(2019)·122 citations
8. 08*

   A GPU compatible quasi-Monte Carlo integrator interfaced to pySecDec

   S.Borowka🇨🇭 · G.Heinrich🇩🇪 · S.Jahn🇩🇪 · S.P.Jones🇨🇭 · M.Kerner🇩🇪 · J.Schlenk🇬🇧

   The purely numerical evaluation of multi-loop integrals and amplitudes can be a viable alternative to analytic approaches, in particular in the presence of several mass scales, provided sufficient accuracy can be achieved in an acceptable amount of time. For many multi-loop integrals, the fraction of time required to perform the numerical integration is significant and it is therefore beneficial to have efficient and well-implemented numerical integration methods. With this goal in mind, we present a new stand-alone integrator based on the use of (quasi-Monte Carlo) rank-1 shifted lattice rules. For integrals with high variance we also implement a variance reduction algorithm based on fitting a smooth function to the inverse cumulative distribution function of the integrand dimension-by-dimension. Additionally, the new integrator is interfaced to pySecDec to allow the straightforward evaluation of multi-loop integrals and dimensionally regulated parameter integrals. In order to make use of recent advances in parallel computing hardware, our integrator can be used both on CPUs and CUDA compatible GPUs where available.

   hep-phComput.Phys.Commun.(2019)·148 citations
9. 09*

   Numerical evaluation of multi-loop integrals

   Stephan Jahn🇩🇪

   We present updates on the development of pySecDec, a toolbox to numerically evaluate parameter integrals in the context of dimensional regularization. We discuss difficulties with loop integrals in the special kinematic condition where the squared momentum of a leg is equal to the squared mass of a propagator. We further discuss some features of a Quasi Monte Carlo (QMC) integrator that can optionally run on Graphics Processing Units (GPUs).

   hep-phPoS(2018)·3 citations
10. 10*

    Description of the ${\Xi }_c$ and ${\Xi }_b$ states as molecular states

    Q. X. Yu🇨🇳 · R. Pavao🇪🇸 · V. R. Debastiani🇪🇸 · E. Oset🇪🇸

    In this work we study several ${\Xi }_c$ and ${\Xi }_b$ states dynamically generated from the meson-baryon interaction in coupled channels, using an extension of the local hidden gauge approach in the Bethe-Salpeter equation. These molecular states appear as poles of the scattering amplitudes, and several of them can be identified with the experimentally observed ${\Xi }_c$ states, including the ${\Xi }_c(2790)$, ${\Xi }_c(2930)$, ${\Xi }_c(2970)$, ${\Xi }_c(3055)$ and ${\Xi }_c(3080)$. Also, for the recently reported ${\Xi }_b(6227)$ state, we find two poles with masses and widths remarkably close to the experimental data, for both the $J^P=1/2^{-}$ and $J^P=3/2^{-}$ sectors.

    hep-phEPJC(2019)·63 citations
11. 11*

    Electroweak Baryogenesis above the Electroweak Scale

    Alfredo Glioti🇨🇭 · Riccardo Rattazzi🇨🇭 · Luca Vecchi🇨🇭

    Conventional scenarios of electroweak (EW) baryogenesis are strongly constrained by experimental searches for CP violation beyond the SM. We propose an alternative scenario where the EW phase transition and baryogenesis occur at temperatures of the order of a new physics threshold $\Lambda$ far above the Fermi scale, say, in the $100-1000$ TeV range. This way the needed new sources of CP-violation, together with possible associated flavor-violating effects, decouple from low energy observables. The key ingredient is a new CP- and flavor-conserving sector at the Fermi scale that ensures the EW symmetry remains broken and sphalerons suppressed at all temperatures below $\Lambda$. We analyze a minimal incarnation based on a linear $O(N)$ model. We identify a specific large-$N$ limit where the effects of the new sector are vanishingly small at zero temperature while being significant at finite temperature. This crucially helps the construction of realistic models. A number of accidental factors, ultimately related to the size of the relevant SM couplings, force $N$ to be above $\sim 100$. Such a large $N$ may seem bizarre, but it does affect the simplicity of the model and in fact it allows us to carry out a consistent re-summation of the leading contributions to the thermal effective potential. Extensions of the SM Higgs sector can be compatible with smaller values $N\sim 20-30$. Collider signatures are all parametrically suppressed by inverse powers of $N$ and may be challenging to probe, but present constraints from direct dark matter searches cannot be accommodated in the minimal model. We discuss various extensions that satisfy all current bounds. One of these involves a new gauge force confining at scales between $\sim 1$ GeV and the weak scale.

    hep-phJHEP(2019)·77 citations
12. 12*

    Anatomy of Heavy Gauge Bosons in a Left-Right Supersymmetric Model

    Biplob Bhattacherjee🇮🇳 · Najimuddin Khan🇮🇳 · Ayon Patra🇮🇳

    We perform a detailed study of the various decay channels of the heavy charged and neutral gauge bosons ($W_R$ and $Z_R$ respectively) in a left-right supersymmetric (LRSUSY) framework. The decay branching ratios of the $W_R$ and $Z_R$ bosons depend significantly on the particle spectrum and composition of the SUSY states. We show several combinations of mass spectrum for the SUSY particles to facilitate the decay of these heavy gauge bosons into various combinations of final states. Finally, we choose two benchmark points and perform detailed collider simulations for these heavy gauge bosons in the context of the high energy and high luminosity run of the large hadron collider. We analyze two SUSY cascade decay channels -- mono-$W$ + $\text{slashed}{E}_T$ and mono-$Z$ + $\text{slashed}{E}_T$ along with the standard dilepton and dijet final states. Our results show that the existence of these heavy gauge bosons can be ascertained in the direct decay channels of dilepton and dijet whereas the other two channels will be required to establish the supersymmetric nature of this model.

    hep-phPRD(2019)·5 citations
13. 13*

    Direct Constraints, Flavor Physics, and Flavor Anomalies in Composite Higgs Models

    Peter Stangl🇫🇷

    Composite Higgs models (CHMs) offer an elegant solution to the naturalness problem of the Standard Model (SM). Their direct effects at particle colliders like the Large Hadron Collider (LHC) are thus of central interest. While no direct effects have been observed so far, there are recent indirect hints for new physics (NP) coming from measurements of rare B meson decays. This thesis studies direct collider constraints on CHMs as well as the question if these models can explain the hints for NP in rare B decays. The first part of this thesis gives a self-contained introduction to all main concepts of CHMs used in the remainder of the work. These concepts are then applied in several phenomenological analyses. In the context of global numerical analyses of two explicit CHMs, the direct constraints on vector, fermion and scalar resonances are studied in detail. The prospects of various decay channels for observing or excluding still viable parameter points of the considered models are discussed. Model independent analyses of the hints for NP in rare B decays are performed in the context of the $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ anomaly as well as the hints for violation of lepton flavor universality (LFU) found in measurements of the observables $R_K$ and $R_{K^{\ast }}$. A simple CHM is presented that can explain the anomalies in rare B decays by partially composite left-handed muons. The flavor physics of a much more ambitious model, which is based on a UV completion of effective CHMs called fundamental partial compositeness (FPC), is investigated in detail. Taking into account all relevant constraints from electroweak scale physics and low-energy flavor observables, it is shown that this model can explain the anomalies found in rare B decays.

    hep-ph5 citations
14. 14*

    Stochastic gravitational waves from spin-3/2 fields -- Hunting SUSY in the sky

    Karim Benakli🇫🇷 · Yifan Chen🇫🇷 · Peng Cheng🇫🇷 · Gaëtan Lafforgue-Marmet🇫🇷

    Stochastic gravitational waves can be produced during the preheating when out-of-equilibrium particles are produced with an anisotropic stress-tensor. We discuss the case where these particles carry spin 3/2. We compute the spectrum of the gravitational waves generated by the transverse and longitudinal components. We find a different scaling of the spectrum near the peak and the longitudinal components lead to an enhancement when compared to spin-1/2 fermions with Yukawa couplings. We note, as expected, that the corresponding typical frequency is too high for the current observation and calls for ultra-high frequency gravitational wave detectors in the future.

    hep-phastro-ph.COgr-qchep-thPRD(2019)·8 citations
15. 15*

    Current status of ${\epsilon }^{\prime }/\epsilon$ in the Standard Model

    Hector Gisbert🇪🇸

    A recent lattice prediction of ${\epsilon }^{\prime }/\epsilon$, with a 2.1 $\sigma$ deviation from the experimental value, has triggered several studies of possible contributions from physics beyond the Standard Model. We have recently updated the SM prediction, including all known short-distance and long-distance contributions, our result $\text{mbox}Re\left({\epsilon }^{\prime }/\epsilon \right)=(15\pm 7)\cdot 10^{-4}$ is in complete agreement with the experimental measurement. In addition, we emphasize on the importance of the long-distance re-scattering of the final pions in $K\to \pi \pi$ for a correct prediction of ${\epsilon }^{\prime }/\epsilon$.

    hep-phhep-exhep-latPoS(2018)·5 citations
16. 16*

    Lepton Flavor Universality tests in $b\to s{\ell }^{+}{\ell }^{-}$ decays at LHCb

    Biplab Dey🇨🇳

    The electroweak sector of the Standard Model contains three generations of charged leptons ${\ell }^{-}\in \{e^{-},{\mu }^{-},{\tau }^{-}\}$ as exact replicas of each other, except for their Yukawa couplings to the Higgs that determine their masses. The Yukawas, and thereby, the masses, are not predicted but are parameters in the theory. A basic tenet in the formalism, known as lepton universality, is equality of the couplings to the electroweak gauge bosons $\{\gamma ,Z,W^{-}\}$ among all three generations, and has mostly stood the test of time. However, precision tests in $B$ decays have recently posed serious challenges to lepton flavor universality, potentially pointing to New Physics beyond the Standard Model. In this work we summarize the latest LHCb results on lepton flavor universality tests in the $b\to s{\ell }^{-}{\ell }^{+}$ electroweak penguin sector and mention further prospects with the upgraded LHCb detector.

    ↳ hep-exhep-phPoS(2019)·1 citation
17. 17*

    Helicity Amplitude Analysis of $J/\psi$ and $\psi (2S)\to \Xi (1530)\bar{\Xi }(1530)$

    Xiongfei Wang🇨🇳 · Bo Li🇫🇷 · Yuanning Gao🇨🇳 · Xinchou Lou🇨🇳

    We perform a helicity amplitude analysis for the processes of $e^{+}{e}^{-}$$\to$$J/\psi ,\psi (2S)\to \Xi (1530)\bar{\Xi }(1530)\to \pi \pi \Xi \bar{\Xi }\to \Lambda \bar{\Lambda }4\pi \to p\bar{p}6\pi$. The joint angular distribution for these processes are obtained, which allows a proper estimation of the detection efficiency using helicity amplitude information. In addition, the sensitivities of measurement of hyperon asymmetry decay parameters for these processes are discussed.

    ↳ hep-exhep-phNPB(2019)·10 citations
18. 18*

    Modular forms of finite modular subgroups from magnetized D-brane models

    Tatsuo Kobayashi🇯🇵 · Shio Tamba🇯🇵

    We study modular transformation of holomorphic Yukawa couplings in magnetized D-brane models. It is found that their products are modular forms, which are non-trivial representations of finite modular subgroups, e.g. $S_3$, $S_4$, $\Delta (96)$ and $\Delta (384)$.

    ↳ hep-thhep-phPRD(2019)·121 citations
19. 19*

    Prior dependence of cosmological constraints on dark matter-radiation interactions

    James A. D. Diacoumis🇦🇺 · Yvonne. Y. Y. Wong🇦🇺

    We explore the issue of prior dependence in the context of one-sided constraints on the dark matter-photon and dark matter-neutrino elastic scattering cross-sections derived from cosmic microwave background (CMB) anisotropies measurements. Testing in particular the linear flat, Jeffreys, and logarithmic flat priors, we find that the former two yield upper limits on the cross-sections that are mutually consistent to within 20%. In contrast, bounds derived under the assumption of the logarithmic flat prior are strongly sensitive to the choice of the lower prior boundary. Indeed, surveying the recent literature, we find that this pathology of the logarithmic prior has resulted in published constraints that are up to an order of magnitude artificially tighter than they should objectively be. Our revised `objective' constraints from the 2015 data of the Planck CMB mission on the present-day scattering cross-sections are ${\sigma }_{\mathrm{DM}-\gamma }<1.72\times 10^{-6}{\sigma }_{\mathrm{T}}(m_{\mathrm{DM}}/\mathrm{GeV})$ and ${\sigma }_{\mathrm{DM}-\gamma }<2.74\times 10^{-15}{\sigma }_{\mathrm{T}}(m_{\mathrm{DM}}/\mathrm{GeV})$ for dark matter-photon interactions scaling as $a^0$ and $a^{-2}$ respectively, where $a$ is the scale factor, and ${\sigma }_{\mathrm{T}}$ the total Thomson scattering cross-section. Their dark matter-neutrino counterparts read ${\sigma }_{\mathrm{DM}-\nu }<2.14\times 10^{-6}{\sigma }_{\mathrm{T}}(m_{\mathrm{DM}}/\mathrm{GeV})$ and ${\sigma }_{\mathrm{DM}-\nu }<2.46\times 10^{-15}{\sigma }_{\mathrm{T}}(m_{\mathrm{DM}}/\mathrm{GeV})$. All have been computed assuming the Jeffreys prior.

    ↳ astro-ph.COhep-phJCAP(2019)·35 citations
20. 20*

    Constraints on Bosonic Dark Matter with Low Threshold Germanium Detector at Kuo-Sheng Reactor Neutrino Laboratory

    Manoj Kumar Singh🇹🇼 · Lakhwinder Singh🇹🇼 · Mehmet Agartioglu🇹🇼 · Vivek Sharma🇹🇼 · Venktesh Singh🇮🇳 · Henry Tsz-king Wong (the TEXONO Collaboration)🇹🇼

    We report results from searches of pseudoscalar and vector bosonic super-weakly interacting massive particles (super-WIMP) in the TEXONO experiment at the Kuo-Sheng Nuclear Power Station, using 314.15 kg days of data from $n$-type Point-Contact Germanium detector. The super-WIMPs are absorbed and deposit total energy in the detector, such that the experimental signatures are spectral peaks corresponding to the super-WIMP mass. Measured data are compatible with the background model, and no significant excess of super-WIMP signals are observed. We derived new upper limits on couplings of electrons with the pseudoscalar and vector bosonic super-WIMPs in the sub-keV mass region, assuming they are the dominant contributions to the dark matter density of our galaxy.

    ↳ hep-exhep-phphysics.ins-detChin.J.Phys.(2019)·17 citations
21. 21*

    On Classical Stability with Broken Supersymmetry

    I. Basile🇮🇹 · J. Mourad🇫🇷 · A. Sagnotti🇮🇹

    We study the perturbative stability of four settings that arise in String Theory, when dilaton potentials accompany the breaking of Supersymmetry, in the USp(32) and U(32) orientifold models, and also in the heterotic SO(16)xSO(16) model. The first two settings are a family of AdS3xS7 orientifold vacua and a family of AdS7xS3 heterotic vacua, supported by form fluxes, with small world-sheet and string-loop corrections within wide ranges of parameters. In both cases we find some unstable scalar perturbations, as a result of mixings induced by fluxes, confirming for the first class of vacua a previous result. However, in the second class they only affect the l=1 modes, so that a Z2 projection induced by an overall internal parity suffices to eliminate them, leading to perturbative stability. Moreover, the constant dilaton profiles of these vacua allow one to extend the analysis to generic potentials, thus exploring the possible effects of higher-order corrections, and we exhibit wide nearby regions of perturbative stability. The solutions in the third setting have nine-dimensional Poincare' symmetry. They include regions with large world-sheet or string-loop corrections, but we show that these vacua have no perturbative instabilities. Finally, the last setting concerns cosmological solutions in ten dimensions where the "climbing" phenomenon takes place: they have bounded string-loop corrections but large world-sheet ones close to the initial singularity. We find that perturbations generally decay, but homogeneous tensor modes exhibit an interesting logarithmic growth that signals a breakdown of isotropy. If the Universe then proceeds to lower dimensions, milder potentials from other branes force all perturbations to remain bounded.

    ↳ hep-thgr-qchep-phJHEP(2019)·91 citations
22. 22*

    The MUonE experiment: a novel way to measure the leading order hadronic contribution to the muon g-2

    Graziano Venanzoni🇮🇹

    We present the status of the MUonE experimental proposal which aims at determining the leading order hadronic contribution to the muon g-2 by measuring the hadronic part of the photon vacuum polarization in the spacelike region. The challenges posed by this measurement on the detector, the proposed solution, and the status of this proposal will be discussed.

    ↳ hep-exhep-phPoS(2019)·9 citations
23. 23*

    Bohmian mechanics for instrumentalists

    H. Nikolic🇭🇷

    We formulate Bohmian mechanics (BM) such that the main objects of concern are macroscopic phenomena, while microscopic particle trajectories only play an auxiliary role. Such a formulation makes it easy to understand why BM always makes the same measurable predictions as standard quantum mechanics (QM), irrespectively of the details of microscopic trajectories. Relativistic quantum field theory (QFT) is interpreted as an effective long-distance theory that at smaller distances must be replaced by some more fundamental theory. Analogy with condensed-matter physics suggests that this more fundamental theory could have a form of non-relativistic QM, offering a simple generic resolution of an apparent conflict between BM and relativistic QFT.

    ↳ quant-phcond-mat.otherhep-phInt.J.Quant.Inf.(2019)·8 citations
24. 24*

    Higgs scalar potential in asymptotically safe quantum gravity

    Jan M. Pawlowski🇩🇪 · Manuel Reichert🇩🇰 · Christof Wetterich🇩🇪 · Masatoshi Yamada🇩🇪

    The effect of gravitational fluctuations on the quantum effective potential for scalar fields is a key ingredient for predictions of the mass of the Higgs boson, understanding the gauge hierarchy problem and a possible explanation of an---asymptotically---vanishing cosmological constant. We find that the quartic self-interaction of the Higgs scalar field is an irrelevant coupling at the asymptotically safe ultraviolet fixed point of quantum gravity. This renders the ratio between the masses of the Higgs boson and top quark predictable. If the flow of couplings below the Planck scale is approximated by the Standard Model, this prediction is consistent with the observed value. The quadratic term in the Higgs potential is irrelevant if the strength of gravity at short distances exceeds a bound that is determined here as a function of the particle content. In this event, a tiny value of the ratio between the Fermi scale and the Planck scale is predicted.

    ↳ hep-thgr-qchep-phPRD(2019)·114 citations
25. 25*

    Inverse Anisotropic Catalysis in Holographic QCD

    Umut Gursoy🇳🇱 · Matti Jarvinen🇳🇱 · Govert Nijs🇳🇱 · Juan F. Pedraza🇳🇱

    We investigate the effects of anisotropy on the chiral condensate in a holographic model of QCD with a fully backreacted quark sector at vanishing chemical potential. The high temperature deconfined phase is a neutral and anisotropic plasma showing different pressure gradients along different spatial directions, similar to the state produced in noncentral heavy-ion collisions. We find that the chiral transition occurs at a lower temperature in the presence of anisotropy. Equivalently, we find that anisotropy acts destructively on the chiral condensate near the transition temperature. These are precisely the same footprints as the "inverse magnetic catalysis" i.e. the destruction of the condensate with increasing magnetic field observed earlier on the lattice, in effective field theory models and in holography. Based on our findings we suggest, in accordance with the conjecture of [1], that the cause for the inverse magnetic catalysis may be the anisotropy caused by the presence of the magnetic field instead of the charge dynamics created by it. We conclude that the weakening of the chiral condensate due to anisotropy is more general than that due to a magnetic field and we coin the former "inverse anisotropic catalysis". Finally, we observe that any amount of anisotropy changes the IR physics substantially: the geometry is ${\text{AdS}}_4\times \mathbb{R}$ up to small corrections, confinement is present only up to a certain scale, and the particles acquire finite widths.

    ↳ hep-thhep-lathep-phJHEP(2019)·57 citations
26. 26*

    Thermal effective potential for the Polyakov loop to higher loop order

    Hiromichi Nishimura🇺🇸 · Chris Korthals-Altes🇳🇱 · Robert D. Pisarski🇺🇸 · Vladimir Skokov🇺🇸

    This is a progress report on the calculation of the effective potential for the Polyakov loop in $SU(N)$ pure gauge theory beyond two-loop order. We introduce a new approach using the Poisson resummation formula to compute sum-integrals with the holonomy. We show partial results for the free energy at order $g^3$ and $g^4$.

    ↳ hep-thhep-lathep-phnucl-thPoS(2019)·4 citations
27. 27*

    On the correlation between the local dark matter and stellar velocities

    Nassim Bozorgnia🇬🇧 · Azadeh Fattahi🇬🇧 · David G. Cerdeno🇬🇧 · Carlos S. Frenk🇬🇧 · Facundo A. Gómez🇨🇱 · Robert J. J. Grand🇩🇪 · Federico Marinacci🇺🇸 · Rüdiger Pakmor🇩🇪

    The dark matter velocity distribution in the Solar neighbourhood is an important astrophysical input which enters in the predicted event rate of dark matter direct detection experiments. It has been recently suggested that the local dark matter velocity distribution can be inferred from that of old or metal-poor stars in the Milky Way. We investigate this potential relation using six high resolution magneto-hydrodynamical simulations of Milky Way-like galaxies of the Auriga project. We do not find any correlation between the velocity distributions of dark matter and old stars in the Solar neighbourhood. Likewise, there are no strong correlations between the local velocity distributions of dark matter and metal-poor stars selected by applying reasonable cuts on metallicity. In some simulated galaxies, extremely metal-poor stars have a velocity distribution that is statistically consistent with that of the dark matter, but the sample of such stars is so small that we cannot draw any strong conclusions.

    ↳ astro-ph.GAastro-ph.COhep-phJCAP(2019)·19 citations
28. 28*

    Inflation and Reheating with a Fermionic Field

    Abhass Kumar🇮🇳

    Inflation has long been the accepted paradigm for understanding the early universe. Most models of inflation have a scalar field acting as the inflaton particle which decays after inflation during a process called reheating into standard model (SM) particles. In this work, we consider a fermion as the inflaton field. Noether symmetry arguments show that an exponentially expanding universe is possible with a fermion if it is coupled non-minimally to gravity. We use such a scenario in this model to study both inflation and reheating. We find relations between the various parameters involved in this model which include the non-minimal coupling strength $\xi$, the mass $m$ and the Yukawa coupling $Y$.

    ↳ gr-qcastro-ph.COhep-phhep-th4 citations
29. 29*

    Microlensing of X-ray Pulsars: a Method to Detect Primordial Black Hole Dark Matter

    Yang Bai🇺🇸 · Nicholas Orlofsky🇺🇸

    Primordial black holes (PBHs) with a mass from $10^{-16}$ to $10^{-11}{M}_{\odot }$ may comprise 100% of dark matter. Due to a combination of wave and finite source size effects, the traditional microlensing of stars does not probe this mass range. In this paper, we point out that X-ray pulsars with higher photon energies and smaller source sizes are good candidate sources for microlensing for this mass window. Among the existing X-ray pulsars, the Small Magellanic Cloud (SMC) X-1 source is found to be the best candidate because of its apparent brightness and long distance from Earth. We have analyzed the existing observation data of SMC X-1 by the RXTE telescope (around 10 days) and found that PBH as 100% of dark matter is close to but not yet excluded. Future longer observation of this source by X-ray telescopes with larger effective areas such as AstroSat, Athena, Lynx, and eXTP can potentially close the last mass window where PBHs can make up all of dark matter.

    ↳ astro-ph.HEastro-ph.GAastro-ph.IMhep-phPRD(2019)·63 citations
30. 30*

    Hadron Formation From Quark-Gluon Plasma Using Lattice QCD At Finite Temperature

    Gouranga C Nayak

    Recently we have reported the correct formulation of the lattice QCD method at the zero temperature to study the hadron formation from the quarks and gluons by incorporating the non-zero boundary surface term in QCD which arises due to the confinement of quarks and gluons inside the finite size hadron. In this paper we extend this to the finite temperature QCD and present the correct formulation of the lattice QCD method at the finite temperature to study the hadron formation from the quark-gluon plasma.

    ↳ nucl-thhep-ph7 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.