Tue·Mar 12, 2019Tuesday·March 12, 2019

1. 01*

   Consistency of the dynamical high-scale type-I seesaw mechanism

   Sanjoy Mandal🇮🇳 · Rahul Srivastava🇪🇸 · José W. F. Valle🇪🇸

   We analyze the consistency of electroweak breaking within the simplest high-scale Standard Model type-I seesaw mechanism. We derive the full two-loop RGEs of the relevant parameters, including the quartic Higgs self-coupling of the Standard Model. For the simplest case of bare "right-handed" neutrino mass terms we find that, with large Yukawa couplings, the Higgs quartic self-coupling becomes negative much below the seesaw scale, so that the model may be inconsistent even as an effective theory. We show, however, that the "dynamical" type-I high-scale seesaw with spontaneous lepton number violation has better stability properties.

   hep-phPRD(2020)·19 citations
2. 02*

   Constraining nuclear physics parameters with current and future COHERENT data

   D.K. Papoulias🇪🇸 · T.S. Kosmas🇬🇷 · R. Sahu🇮🇳 · V.K.B. Kota🇮🇳 · M. Hota🇮🇳

   Motivated by the recent observation of coherent elastic neutrino-nucleus scattering (CE$\nu$NS) at the COHERENT experiment, our goal is to explore its potential in probing important nuclear structure parameters. We show that the recent COHERENT data offers unique opportunities to investigate the neutron nuclear form factor. Our present calculations are based on the deformed Shell Model (DSM) method which leads to a better fit of the recent CE$\nu$NS data, as compared to known phenomenological form factors such as the Helm-type, symmetrized Fermi and Klein-Nystrand. The attainable sensitivities and the prospects of improvement during the next phase of the COHERENT experiment are also considered and analyzed in the framework of two upgrade scenarios.

   hep-phPLB(2020)·96 citations
3. 03*

   Spectroscopic Assignments of the Excited $B$-Mesons

   Stephen Godfrey🇨🇦 · Kenneth Moats🇨🇦

   Excited $B$-mesons have been observed by the D0, CDF, LHCb and CMS experiments. We use the predictions of the relativized quark model to make quark model spectroscopic assignments for these states. We identify the $B_2^{\ast }(5747)$ and $B_1(5721)$ as the $B_2^{\ast }[1^3{P}_2]$ and $B_1[1P_1]$ states and the $B_{s2}^{\ast }(5840)$ and $B_{s1}(5830)$ as the $B_{s2}^{\ast }[1^3{P}_2]$ and $B_{s1}[1P_1]$ states. More information is needed to identify the $B_J(5970)$ and $B_J(5840)$ states and we suggest a number of measurements to make this identification: the determination of their $J^P$ quantum numbers and either confirming or ruling out their decays to the $B\pi$ final state. With the current information available we believe it most likely that the $B_J(5970)$ is the $B^{\ast }[2^3{S}_1]$ state, with the $B_J(5840)$ needing confirmation.

   hep-phhep-exnucl-thEPJA(2019)·9 citations
4. 04*

   Light-Cone Sum Rules Analysis of ${\Xi }_{Q{Q}^{\prime }q}\to {\Lambda }_{Q^{\prime }}$ Weak Decays

   Yu-Ji Shi🇨🇳 · Ye Xing🇨🇳 · Zhen-Xing Zhao🇨🇳

   We analyze the weak decay of doubly-heavy baryon decays into anti-triplets ${\Lambda }_Q$ with light-cone sum rules. To calculate the decay form factors, both bottom and charmed anti-triplets ${\Lambda }_b$ and ${\Lambda }_c$ are described by the same set of leading twist light-cone distribution functions. With the obtained form factors, we perform a phenomenology study on the corresponding semi-leptonic decays. The decay widths are calculated and the branching ratios given in this work are expected to be tested by future experimental data, which will help us to understand the underlying dynamics in doubly-heavy baryon decays.

   hep-phEPJC(2019)·49 citations
5. 05*

   Electrical conductivity and Hall conductivity of hot and dense hadron gas in a magnetic field: a relaxation time approach

   Arpan Das🇮🇳 · Hiranmaya Mishra🇮🇳 · Ranjita K. Mohapatra🇮🇳

   We estimate the electrical conductivity and the Hall conductivity of hot and dense hadron gas using the relaxation time approximation of the Boltzmann transport equation in the presence of electromagnetic field. We have investigated the temperature and the baryon chemical potential dependence of these transport coefficients in presence of magnetic field. The explicit calculation is performed within the ambit of the hadron resonance gas model. We find that the electrical conductivity decreases in the presence of magnetic field. The Hall conductivity on the other hand shows a non monotonic behavior with respect to the dependence on magnetic field. We argue that for a pair plasma (particle-anti particle plasma) where ${\mu }_B=0$, Hall conductivity vanishes. Only for non vanishing baryon chemical potential Hall conductivity has non zero value. We also estimate the electrical conductivity and the Hall conductivity as a function of the center of mass energy along the freeze out curve as may be relevant for relativistic heavy ion collision experiments.

   hep-phnucl-thPRD(2019)·51 citations
6. 06*

   $B_{(s)}\to D_{s0}^{\ast }(2317)P(V)$ decays in perturbative QCD approach

   Zhi-Qing Zhang🇨🇳 · Hongxia Guo🇨🇳 · Na Wang🇨🇳 · Hai-Tao Jia🇨🇳

   In this work, we use pQCD approach to calculate 20 $B_{(s)}\to D_{s0}^{\ast }(2317)P(V)$ two body decays by assuming $D_{s0}^{\ast }(2317)$ as a $\bar{c}s$ scalar meson, where $P(V)$ denotes a pseudoscalar (vector) meson. These $B_{(s)}$ decays can serve as an ideal platform to probe the valuable information on the inner structure of the charmed-strange meson $D_{s0}^{\ast }(2317)$, and to explore the dynamics of strong interactions and signals of new physics. These considered decays can be divided into two types: the CKM favored decays and the CKM suppressed decays. The former are induced by $b\to c$ transition, whose branching ratios are larger than $10^{-5}$. The branching fraction of the decay ${\bar{B}}_s^0\to D_{s0}^{\ast +}(2317){\rho }^{-}$ is the largest and reaches about $1.8\times 10^{-3}$, while the branching ratios for the decay ${\bar{B}}_s^0\to D_{s0}^{\ast +}(2317)K^{\ast -}$ and other two pure annihilation decays ${\bar{B}}^0\to D_{s0}^{\ast +}(2317)K^{-},D_{s0}^{\ast +}(2317)K^{\ast -}$ are only at $10^{-5}$ order. Our predictions are consistent well with the results given by the light cone sum rules approach. These decays are most likely to be measured at the running LHCb and the forthcoming SuperKEKB. The latter are induced by $b\to u$ transition, among of which the channel ${\bar{B}}^0\to D^{\ast -}(2317){\rho }^{+}$ has the largest branching fraction, reaching up to $10^{-5}$ order. Again the pure annihilation decays $B^{-}\to D_{s0}^{\ast -}(2317)\varphi ,{\bar{B}}^0\to D_{s0}^{\ast -}(2317)K^{+}(K^{\ast +}),B^{-}\to D_{s0}^{\ast -}(2317)K^0(K^{\ast 0})$, have the smallest branching ratios, which drop to as low as $10^{-10}\sim 10^{-8}$.

   hep-phPRD(2019)·3 citations
7. 07*

   Multiparticle production and initial quasi-temperature from proton induced carbon collisions at $p_{Lab}=31$ GeV/$c$

   Pei-Pin Yang🇨🇳 · Mai-Ying Duan🇨🇳 · Fu-Hu Liu🇨🇳 · Raghunath Sahoo🇮🇳

   The momentum spectra of charged pions (${\pi }^{+}$ and ${\pi }^{-}$) and kaons ($K^{+}$ and $K^{-}$), as well as protons ($p$), produced in the beam protons induced collisions in a 90-cm-long graphite target [proton-carbon ($p$-C) collisions] at the beam momentum $p_{Lab}=31$ GeV/$c$ are studied in the framework of a multisource thermal model by using Boltzmann distribution and Monte Carlo method. The theoretical model results are approximately in agreement with the experimental data measured by the NA61/SHINE Collaboration. The related free parameters (effective temperature, rapidity shifts, and fraction of non-leading protons) and derived quantities (average transverse momentum and initial quasi-temperature) under given experimental conditions are obtained. It is shown that the considered free parameters and derived quantities to be strongly dependent on emission angle over a range from 0 to 380 mrad and weakly dependent on longitudinal position (graphite target thickness) over a range from 0 to 90 cm.

   hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2020)·2 citations
8. 08*

   Feasibility at the LHC, FCC-he and CLIC for sensitivity estimates on anomalous $\tau$-lepton couplings

   A. Gutiérrez-Rodríguez🇲🇽 · M. Köksal🇹🇷 · A. A. Billur🇹🇷 · M. A. Hernández-Ruíz🇲🇽

   In this paper, we present detailed studies on the feasibility at $pp$, $e^{-}p$ and $e^{+}{e}^{-}$ colliders for model-independent sensitivity estimates on the total cross-section and on the anomalous ${\tau }^{+}{\tau }^{-}\gamma$ interaction through the tau pair production channels $pp\to p\tau \bar{\tau }\gamma p$, $e^{-}p\to e^{-}\tau \bar{\tau }\gamma p$ and $e^{+}{e}^{-}\to e^{+}\tau \bar{\tau }\gamma e^{-}$ at the ${\gamma }^{\ast }{\gamma }^{\ast }\to {\tau }^{+}{\tau }^{-}\gamma$ mode. Measurements of the anomalous couplings of the $\tau$-lepton ${\tilde{a}}_{\tau }$ and ${\tilde{d}}_{\tau }$ provide an excellent opportunity to probing extensions of the Standard Model. We estimate the sensitivity at the $95\%$ Confidence Level, and we consider that the $\tau$-lepton decays leptonically or semi-leptonically. We found that of the three considered colliders, the future CLIC at high energy and high luminosity should provide the best sensitivity on the dipole moments of the $\tau$-lepton ${\tilde{a}}_{\tau }=[-0.00128,0.00105]$ and $|{\tilde{d}}_{\tau }(\mathrm{ecm})|=6.4394\times 10^{-18}$, which show a potential advantage compared to those from LHC and FCC-he.

   hep-ph19 citations
9. 09*

   Extending the constraint for axion-like particles as resonances at the LHC and laser beam experiments

   C. Baldenegro🇺🇸 · S. Hassani🇫🇷 · C. Royon🇺🇸 · L. Schoeffel🇫🇷

   We study the discovery potential of axion-like particles (ALP), pseudo-scalars weakly coupled to Standard Model fields, at the Large Hadron Collider (LHC). Our focus is on ALPs coupled to the electromagnetic field, which would induce anomalous scattering of light-by-light. This can be directly probed in central exclusive production of photon pairs in ultra-peripheral collisions at the LHC in proton and heavy ion collisions. We consider non-standard collision modes of the LHC, such as argon-argon collisions at $\sqrt{s_{NN}}=7$ TeV and proton-lead collisions at $\sqrt{s_{NN}}=8.16$ TeV to access regions in the parameter space complementary to the ones previously considered for lead-lead or proton-proton collisions. In addition, we show that, using laser beam interactions, we can constrain ALPs as resonant deviations in the refractive index, induced by anomalous light-by-light scattering effects. If we combine the aforementioned approaches, ALPs can be probed in a wide range of masses from the eV scale up to the TeV scale.

   hep-phphysics.opticsPLB(2019)·52 citations
10. 10*

    Transverse Momentum Spectra of Pions at LHC Energies

    Abdel Nasser Tawfik (Nile U., ECTP & WLCAPP, Cairo)🇪🇬

    In order to characterize the transverse momentum spectra of positive pions measured in the ALICE experiment, two thermal approaches are utilized; one is based on degeneracy of non-perfect Bose-Einstein gas and the other imposes an {\it ad-hoc} finite pion-chemical potential. The inclusion of missing haron states and the out-of-chemical equilibrium greatly contribute to the excellent characterization of pion production. The excellent reproduction of the experimental data can be understood as a manifestation of not-yet-regarded anomalous pion-production, which likely contribute to the long-standing debate on the {\it "anomalous"} proton-to-pion ratios at top RHIC and LHC energies.

    hep-phnucl-thAdv.High Energy Phys.(2019)·8 citations
11. 11*

    Radiative generation of realistic neutrino mixing with $A4$

    Soumita Pramanick🇮🇳

    Radiative generation of realistic mixing in neutrino sector is studied at one-loop level in a scotogenic $A4\times Z_2$ symmetric framework. A scheme of obtaining non-zero ${\theta }_{13}$ through small mass splitting in right-handed neutrino sector is proposed. The model consists of three right-handed neutrinos, two of which were required to be degenerate in masses to yield the common structure of the left-handed neutrino mass matrix that corresponds to ${\theta }_{13}=0$, ${\theta }_{23}=\pi /4$ and any ${\theta }_{12}^0$ in particular the choices specific to the Tribimaximal (TBM), Bimaximal (BM) and Golden Ratio (GR) mixings. Non-zero ${\theta }_{13}$, deviations of ${\theta }_{23}$ from maximality and small corrections to the solar mixing angle ${\theta }_{12}$ can be generated in one stroke by shifting from this degeneracy in the right-handed neutrino sector by a small amount. The lightest among the three $Z_2$ odd inert $SU(2{)}_L$ doublet scalars present in the model can be a potential dark matter candidate.

    hep-phNPB(2021)·20 citations
12. 12*

    S-wave contributions in ${\bar{B}}_s^0\to (D^0,{\bar{D}}^0){\pi }^{+}{\pi }^{-}$ within perturbative QCD approach

    Ye Xing🇨🇳 · Zhi-Peng Xing🇨🇳

    The ${\bar{B}}_s^0\to (D^0,{\bar{D}}^0){\pi }^{+}{\pi }^{-}$ is induced by the $b\to c\bar{u}s$/$b\to u\bar{c}s$ transition, and can interfere if a CP-eigenstate $D_{\mathrm{CP}}$ is formed. The interference contribution is sensitive to the CKM angle $\gamma$. In this work, we study S-wave ${\pi }^{+}{\pi }^{-}$ contributions to the process in the perturbative QCD factorization. Under the factorization framework, we adopt two-meson light-cone distribution amplitudes, whose normalization is parametrized by the S-wave time-like two-pion form factor with the resonance contributions from $f_0(500)$, $f_0(980),f_0(1500),f_0(1790)$. We find the branching ratios of ${\bar{B}}_s^0\to (D^0,{\bar{D}}^0)({\pi }^{+}{\pi }^{-}{)}_S$ can reach the order of $10^{-6}$, and significant interferences exist in ${\bar{B}}_s^0\to D_{CP}({\pi }^{+}{\pi }^{-}{)}_S$. The future measurement can not only provide useful constraints on the CKM angle $\gamma$ but is also helpful to explore the multi-body decay mechanism of heavy mesons.

    hep-phCPC(2019)·26 citations
13. 13*

    Thoughts on opportunities in high-energy nuclear collisions

    Federico Antinori · Peter Braun-Munzinger🇩🇪 · Jan-Fiete Grosse-Oetringhaus🇨🇭 · Ulrich Heinz🇺🇸 · Barbara Jacak🇺🇸 · Peter Jacobs · Alexander Kalweit🇨🇭 · Volker Koch🇺🇸 · Yen-Jie Lee🇺🇸 · Marco Van Leeuwen🇳🇱 · Silvia Masciocchi · Guilherme Teixeira De Almeida Milhano🇵🇹 and 18 other authors

    This document reflects thoughts on opportunities from high-energy nuclear collisions in the 2020s.

    hep-ph1 citation
14. 14*

    Wave Functions and Leptonic Decays of Bottom Mesons In the Relativistic Potential Model

    Hao-Kai Sun🇨🇳 · Mao-Zhi Yang🇨🇳

    We study the wave functions and purely leptonic decays of $b$-flavored mesons (pseudoscalars, vector mesons, and higher excited states that are well established in experiment) in the relativistic potential model based on our previous works. The wave functions are obtained by solving the wave equation including the spin-spin and spin-orbit corrections in the effective potential. The decay constants of $B$, $B^{\ast }$ and some of their excited states that have been found in experiment are calculated with these wave functions. Then the branching fractions of the purely leptonic decay modes of these bottom mesons are studied. Our results are in well agreement with experiment data for decay modes that have been measured in experiments. We also provide predictions for some yet unmeasured channels, which are useful for experimental test in the future.

    hep-phPRD(2019)·19 citations
15. 15*

    The exponent of the longitudinal structure function $F_L$ at low $x$

    G.R.Boroun🇮🇷

    We present a set of formula to extract exponents of the longitudinal structure function and reduced cross section from the Regge-like behavior at small $x$. The exponents are found to be independent of $Q^2$ at NNLO analysis. As a result, we show that the reduced cross section exponents do not have the same behavior at some values of $x$. This difference predicts the non-linear effects and some evidence for shadowing and antishadowing at LHeC. Also the ratio $\frac{F_2}{\sigma }$ is calculated and compared with the corresponding HERA data. Our calculations show a very good agreement with the DIS experimental data throughout the small values of $x$.

    hep-phEur.Phys.J.Plus(2020)·7 citations
16. 16*

    Master integrals of a planar double-box family for top-quark pair production

    Long-Bin Chen🇨🇳 · Jian Wang🇩🇪

    We calculate analytically the master integrals of a planar double-box family for top-quark pair production using the method of differential equations. With a proper choice of the bases, the differential equations can be transformed to the $d$-log form. The square roots of the kinematic variables in the differential equations can be rationalized by defining two dimensionless variables. We find that all the boundary conditions can be fully fixed either by simple integrals or regularity conditions at some special kinematic points. The analytic results for thirty-three master integrals at general kinematics are all expressed in terms of multiple polylogarithms up to transcendental weight four.

    hep-phPLB(2019)·9 citations
17. 17*

    Doubly Heavy Baryons Expanded in $1/m_Q$

    Takayuki Matsuki🇯🇵

    Starting from the semirelativistic Hamiltonian for a doubly heavy baryon system ($QQq$) with Coulomb and linear confining scalar potentials, and operating the naive Foldy-Wouthuysen-Tani transformation on two heavy quarks, I construct a formulation how to calculate mass spectra and wave functions of doubly heavy baryons. Based on our formulation, their masses and wave functions are expanded in $1/m_Q$ with a heavy quark mass $m_Q$ and the $\lambda$ mode lowest-order equation is examined carefully to obtain a complete set of eigenfunctions. I claim that the $\rho$ mode wave function should be given by other nonrelativistic methods, e.g., the Godfrey-Isgur model to give a complete wave function for a doubly heavy baryon.

    hep-phhep-exnucl-thJPS Conf.Proc.(2019)·1 citation
18. 18*

    Hidden-charm pentaquark formation in antiproton - deuterium collisions

    M.B. Voloshin🇺🇸

    The possibility of observing formation of hidden-charm pentaquarks as $s$-channel resonances in antiproton - deuteron collisions is discussed. It is pointed out that the masses of the reported by LHCb pentaquark resonances in the $J/\psi p$ channel are very close to a special value of the mass at which formation of a pentaquark by antiproton incident on a deuteron at rest requires exactly the same momentum of the $\bar{p}$ as needed for the formation in the $s$ channel of the charmonium resonance in $\bar{p}p$ collisions with the proton being at rest. For this reason the former process can be rather completely described within the notion of the deuteron being a shallow bound state of two nucleons without resorting to models describing its short-distance structure. It is argued that a similar kinematical coincidence can be expected for (yet) hypothetical pentaquark resonances in the ${\eta }_{c}N$ channel, and that these can be sought for once antiproton - deuterium collisions become available for experimentation.

    hep-phhep-exPRD(2019)·8 citations
19. 19*

    Heavy pentaquark spectroscopy in the diquark model

    Floriana Giannuzzi🇮🇹

    $Q{Q}^{\prime }qq\bar{q}$ pentaquarks are studied in a potential model, under the hypothesis that they are composite objects of two diquarks and one antiquark. The interaction between two colored objects includes two contributions, one based on the $q\bar{q}$ potential in QCD, computed in the gauge/string duality approach, and another describing the spin-spin interaction. The model has been extended to investigate pentaquarks with different quark content, as $Qqqq\bar{q}$ and $Qqqq\bar{Q}$, the latter including the states observed by LHCb, $P_c(4380{)}^{+}$ and $P_c(4450{)}^{+}$, later updated, with a new data sample, to $P_c(4312{)}^{+}$, $P_c(4440{)}^{+}$, and $P_c(4457{)}^{+}$.

    hep-phPRD(2019)·53 citations
20. 20*

    Spinorial Structure of $O(3)$ and Application to Dark Matter

    Teruyuki Kitabayashi🇯🇵 · Masaki Yasuè🇯🇵

    An $O(3)$ spinor, $\Phi$, as a doublet denoted by $2_D$ consists of an $SO(3)$ spinor, $\varphi$, and its complex conjugate, ${\varphi }^{\ast }$, which form $\Phi ={\left(\varphi ,{\varphi }^{\ast }\right)}^T$ to be identified with a Majorana-type spinor of $O(4)$. The four gamma matrices ${\Gamma }_{\mu }$ ($\mu =1\sim 4$) are given by ${\Gamma }_i=\text{diag.}\left({\tau }_i,{\tau }_i^{\ast }\right)$ ($i=1,2,3$) and ${\Gamma }_4=-{\tau }_2\otimes {\tau }_2$, where ${\tau }_i$ denote the Pauli matrices. The rotations and axis-reflections of $O(3)$ are, respectively, generated by ${\Sigma }_{ij}$ and ${\Sigma }_{i4}$, where ${\Sigma }_{\mu \nu }=[{\Gamma }_{\mu },{\Gamma }_{\nu }]/2i$. While $\Phi$ is regarded as a scalar, a fermionic $O(3)$ spinor is constructed out of an $SO(3)$ doublet Dirac spinor and its charge conjugate. These $O(3)$ spinors are restricted to be neutral and cannot carry the standard model quantum numbers because they contain particles and antiparticles. Our $O(3)$ spinors serve as candidates of dark matter. The $O(3)$ symmetry in particle physics is visible when the invariance of interactions is considered by explicitly including their complex conjugates. It is possible to introduce a dark gauge symmetry based on $SO(3)\times {\mathbf{Z}}_2$ equivalent to $O(3)$, where the ${\mathbf{Z}}_2$ parity is described by a $U(1)$ charge giving 1 for a particle and $-1$ for an antiparticle. The $SO(3)$ and $U(1)$ gauge bosons turn out to transform as the axial vector of $O(3)$ and the pseudoscalar of $O(3)$, respectively. This property is related to the consistent definition of the nonabelian field strength tensor of $O(3)$ or of the U(1) charge of the O(3)-transformed spinor. To see the feasibility of our dark matter models, we discuss scalar dark matter phenomenology based on the dark $U(1)$ gauge model.

    hep-phNPB(2020)·0 citations
21. 21*

    The Inert Doublet Model at current and future colliders

    Jan Kalinowski🇵🇱 · Wojciech Kotlarski🇩🇪 · Tania Robens🇭🇷 · Dorota Sokolowska🇧🇷 · Alexander Filip Zarnecki🇵🇱

    We discuss the status of the Inert Doublet Model, a two-Higgs doublet model that obeys a discrete Z2 symmetry and provides a dark matter candidate. We discuss all current theoretical and experimental constraints on the model as well as discovery prospects at current and future colliders.

    hep-phJ.Phys.Conf.Ser.(2020)·11 citations
22. 22*

    Quark fragmentation as a probe of dynamical mass generation

    Alberto Accardi (Hampton U. and Jefferson Lab)🇺🇸 · Andrea Signori (Argonne National Laboratory)🇺🇸

    We address the propagation and hadronization of a struck quark by studying the gauge invariance of the color-averaged cut quark propagator, and by relating this to the single inclusive quark fragmentation correlator by means of new sum rules. Using suitable Wilson lines, we provide a gauge-invariant definition for the mass of the color-averaged dressed quark and decompose this into the sum of a current and an interaction-dependent component. The latter, which we argue is an order parameter for dynamical chiral symmetry breaking, also appears in the sum rule for the twist-3 $\tilde{E}$ fragmentation function, providing a specific experimental way to probe the dynamical generation of mass in Quantum Chromo Dynamics.

    hep-phhep-exnucl-thPLB(2019)·23 citations
23. 23*

    Conformal theory of everything

    F. F. Faria🇧🇷

    By using conformal symmetry we unify the standard model of particle physics with gravity in a consistent quantum field theory which describes all the fundamental particles and forces of nature.

    hep-phhep-th3 citations
24. 24*

    Search for light sterile neutrinos from $W^{\pm }$ decays at the LHC

    Claudio O. Dib🇨🇱 · Choong Sun Kim🇰🇷 · Sebastian Tapia Araya🇺🇸

    We study the feasibility to observe sterile neutrinos with masses in the range 5 GeV $<m_N<20$ GeV at the LHC, using exclusive semileptonic modes involving pions, $W\to \ell N\to \pi \ell \ell ,2\pi \ell \ell$ and $3\pi \ell \ell$. We thus cover a mass window that is between what can be studied in meson factories and high energy colliders. We run simulations for these exclusive events, where pions should be distinguished from the background provided the neutrino decay exhibits a vertex displacement from its production point. In a previous work we have estimated the theoretical rates and here we analyze the observability of the processes at the LHC, given the fact that exclusive hadronic states may be difficult to identify. We study the sensitivity bounds for the observation and discovery of sterile neutrinos in the above mass range. By the end of Run-3, current bounds on heavy-to-light lepton mixings in the lower mass end ($\sim 5$ GeV) could be improved by about an order of magnitude to $|U_{\ell N}{|}^2\sim 5\times 10^{-6}$, and the High-Luminosity LHC could reach $|U_{\ell N}{|}^2\lesssim 3\times 10^{-7}$ in the mass range below 11 GeV. Studying in addition equal sign and opposite sign dileptons, the Majorana or Dirac character of the sterile neutrino could be revealed.

    hep-phPRD(2020)·17 citations
25. 25*

    Neutrino Mass from Cosmology: Probing Physics Beyond the Standard Model

    Cora Dvorkin🇺🇸 · Martina Gerbino🇺🇸 · David Alonso🇬🇧 · Nicholas Battaglia🇺🇸 · Simeon Bird🇺🇸 · Ana Diaz Rivero🇺🇸 · Andreu Font-Ribera🇬🇧 · George Fuller🇺🇸 · Massimiliano Lattanzi🇮🇹 · Marilena Loverde🇺🇸 · Julian B. Muñoz🇺🇸 · Blake Sherwin🇬🇧 · Anže Slosar🇺🇸 · Francisco Villaescusa-Navarro🇺🇸

    Recent advances in cosmic observations have brought us to the verge of discovery of the absolute scale of neutrino masses. Nonzero neutrino masses are known evidence of new physics beyond the Standard Model. Our understanding of the clustering of matter in the presence of massive neutrinos has significantly improved over the past decade, yielding cosmological constraints that are tighter than any laboratory experiment, and which will improve significantly over the next decade, resulting in a guaranteed detection of the absolute neutrino mass scale.

    ↳ astro-ph.COhep-ph95 citations
26. 26*

    Beyond the Poles in Attractor Models of Inflation

    Sotirios Karamitsos🇬🇧

    We offer a geometric interpretation of attractor theories with singular kinetic terms as a union of multiple canonical models. We demonstrate that different domains (separated by poles) can drastically differ in their phenomenology. We illustrate this with the help of a "master model" that leads to distinct predictions depending on which side of the pole the field evolves before examining the more realistic example of $\alpha$-attractor models. Such models lead to quintessential inflation within the poles when featuring an exponential potential. However, beyond the poles, we discover a novel behaviour: the scalar field responsible for the early-time acceleration of the Universe may reach the boundary of the field-space manifold, indicating that the theory is incomplete and that a boundary condition must be imposed in order to determine its late-time behaviour. If the evolution of the field is arrested before this happens, however, we discover that quintessence can be achieved without a potential offset. Turning to multifield models with singular kinetic terms, we see that poles generalise straightforwardly to singular curves, which act as "model walls" between distinct pole-free inflationary models. As an example, we study a simple two-field $\alpha$-attractor-inspired model, whose evolution of isocurvature perturbations is sensitive to where the non-canonical field begins its trajectory. We finally discuss initial conditions in attractor theories, where the existence of multiple disconnected canonical models implies that we must make a fundamental choice: in which domain we impose a distribution for the inflaton in order to then determine the likelihood of inflation.

    ↳ hep-thgr-qchep-phJCAP(2019)·22 citations
27. 27*

    Stimulated emission of relic gravitons and their super-Poissonian statistics

    Massimo Giovannini🇨🇭

    The degree of second-order coherence of the relic gravitons produced from the vacuum is super-Poissonian and larger than in the case of a chaotic source characterized by a Bose-Einstein distribution. If the initial state does not minimize the tensor Hamiltonian and has a dispersion smaller than its averaged multiplicity, the overall statistics is by definition sub-Poissonian. Depending on the nature of the sub-Poissonian initial state, the final degree of second-order coherence of the quanta produced by stimulated emission may diminish (possibly even below the characteristic value of a chaotic source) but it always remains larger than one (i.e. super-Poissonian). When the initial statistics is Poissonian (like in the case of a coherent state or for a mixed state weighted by a Poisson distribution) the degree of second-order coherence of the produced gravitons is still super-Poissonian. Even though the quantum origin of the relic gravitons inside the Hubble radius can be effectively disambiguated by looking at the corresponding Hanbury Brown-Twiss correlations, the final distributions caused by different initial states maintain their super-Poissonian character which cannot be altered.

    ↳ gr-qcastro-ph.COhep-phhep-thMod.Phys.Lett.A(2019)·6 citations
28. 28*

    Spinning particle orbits around a black hole in an expanding background

    I. Antoniou🇬🇷 · D. Papadopoulos🇬🇷 · L. Perivolaropoulos🇬🇷

    We investigate analytically and numerically the orbits of spinning particles around black holes in the post Newtonian limit and in the presence of cosmic expansion. We show that orbits that are circular in the absence of spin, get deformed when the orbiting particle has spin. We show that the origin of this deformation is twofold: a. the background expansion rate which induces an attractive (repulsive) interaction due to the cosmic background fluid when the expansion is decelerating (accelerating) and b. a spin-orbit interaction which can be attractive or repulsive depending on the relative orientation between spin and orbital angular momentum and on the expansion rate.

    ↳ gr-qcastro-ph.COhep-phhep-thClass.Quant.Grav.(2019)·13 citations
29. 29*

    Disformally Coupled Scalar Fields and Inspiralling Trajectories

    Philippe Brax🇫🇷 · Anne-Christine Davis🇬🇧 · Adrien Kuntz🇫🇷

    We show how a nearly massless scalar field conformally and disformally coupled to matter can affect the dynamics of two bodies in their inspiralling phase before merging. We discuss both the conservative dynamics, e.g. how the energy of the bound system is corrected by the conformal and disformal interactions, and the dissipative part where scalars and gravitons are emitted. The first disformal correction to the Einstein-Infeld-Hoffmann Lagrangian is obtained using both the Fokker method relying on the equations of motion and an Effective Field Theory approach using Feynman diagrams. This leads to a correction to the energy functional at the 2PN level for eccentric orbits, which vanishes for circular orbits up to the 7PN order. The dissipative power from the disformal interaction gives a correction to the monopole and quadrupole terms in the presence of a conformal coupling. Although this correction vanishes for circular orbits at leading order, this is not the case for elliptical orbits allowing us to derive a bound on the disformal coupling from the time drift of the period for the Hulse-Taylor binary pulsar, which is slightly stronger than the one from fifth force tests. We conclude that the prospect of observing disformal effects for inspiralling systems lies in the accurate monitoring of eccentric trajectories as expected for the LISA experiment.

    ↳ gr-qcastro-ph.COhep-phPRD(2019)·23 citations
30. 30*

    Neutrino Topology Reconstruction at DUNE and Applications to Searches for Dark Matter Annihilation in the Sun

    Carsten Rott🇰🇷 · DongYoung Jeong🇰🇷 · Jason Kumar🇺🇸 · David Yaylali🇺🇸

    We consider a new technique for neutrino energy and topology reconstruction at DUNE. In particular, we show that when the direction of the incoming neutrino is known, one can use the measured directions of the outgoing leptonic and hadronic particles to reconstruct poorly-measured quantities, such as the hadronic cascade energy. We show that this alternative technique yields an energy resolution which is comparable to current reconstruction methods which sum measured energies. As a proof of concept we apply this new reconstruction method to a search for dark matter annihilation in the Sun. We show that the use of directional information from both the leptonic and hadronic interaction products allows one to effectively reject backgrounds and isolate the signal, giving competitive sensitivities.

    ↳ astro-ph.HEhep-phJCAP(2019)·12 citations
31. 31*

    Localized rainbows in the QCD phase diagram

    Jan Maelger🇫🇷 · Urko Reinosa🇫🇷 · Julien Serreau🇫🇷

    We study the phase diagram of strongly interacting matter with light quarks using a recently proposed, small parameter approach to infrared QCD in the Landau gauge. This is based on an expansion with respect to both the inverse number of colors and the pure Yang-Mills coupling in the presence of a Curci-Ferrari mass term. At leading order, this leads to the well-known rainbow equation for the quark propagator with a massive gluon propagator. We solve the latter at nonzero temperature and chemical potential using a simple semi-analytic approximation known to capture the essence of chiral symmetry breaking in the vacuum. In the chiral limit, we find a tricritical point which becomes a critical endpoint in the presence of a nonzero bare quark mass, in agreement with the results of nonperturbative functional methods and model calculations. This supports the view that the present approach allows for a systematic study of the QCD phase diagram in a controlled expansion scheme.

    ↳ hep-thhep-phnucl-thPRD(2020)·21 citations
32. 32*

    Fundamental Physics with High-Energy Cosmic Neutrinos

    Markus Ackermann🇩🇪 · Markus Ahlers🇩🇰 · Luis Anchordoqui🇺🇸 · Mauricio Bustamante🇩🇪 · Amy Connolly🇺🇸 · Cosmin Deaconu🇺🇸 · Darren Grant🇨🇦 · Peter Gorham🇺🇸 · Francis Halzen🇺🇸 · Albrecht Karle🇺🇸 · Kumiko Kotera🇫🇷 · Marek Kowalski🇩🇪 and 7 other authors

    High-energy cosmic neutrinos can reveal new fundamental particles and interactions, probing energy and distance scales far exceeding those accessible in the laboratory. This white paper describes the outstanding particle physics questions that high-energy cosmic neutrinos can address in the coming decade. A companion white paper discusses how the observation of cosmic neutrinos can address open questions in astrophysics. Tests of fundamental physics using high-energy cosmic neutrinos will be enabled by detailed measurements of their energy spectrum, arrival directions, flavor composition, and timing.

    ↳ astro-ph.HEastro-ph.COhep-phBull.Am.Astron.Soc.(2019)·81 citations
33. 33*

    Astrophysics Uniquely Enabled by Observations of High-Energy Cosmic Neutrinos

    Markus Ackermann🇩🇪 · Markus Ahlers🇩🇰 · Luis Anchordoqui🇺🇸 · Mauricio Bustamante🇩🇪 · Amy Connolly🇺🇸 · Cosmin Deaconu🇺🇸 · Darren Grant🇨🇦 · Peter Gorham🇺🇸 · Francis Halzen🇺🇸 · Albrecht Karle🇺🇸 · Kumiko Kotera🇫🇷 · Marek Kowalski🇩🇪 and 7 other authors

    High-energy cosmic neutrinos carry unique information about the most energetic non-thermal sources in the Universe. This white paper describes the outstanding astrophysics questions that neutrino astronomy can address in the coming decade. A companion white paper discusses how the observation of cosmic neutrinos can address open questions in fundamental physics. Detailed measurements of the diffuse neutrino flux, measurements of neutrinos from point sources, and multi-messenger observations with neutrinos will enable the discovery and characterization of the most energetic sources in the Universe.

    ↳ astro-ph.HEastro-ph.COhep-phBull.Am.Astron.Soc.(2019)·101 citations
34. 34*

    On Axion Reheating in the String Landscape

    James Halverson🇺🇸 · Cody Long🇺🇸 · Brent Nelson🇺🇸 · Gustavo Salinas🇺🇸

    We demonstrate that asymmetric reheating arises in a large ensemble of string compactifications with many axions and gauged dark sectors. This phenomenon may help avoid numerous cosmological problems that may arise if the sectors were reheated democratically. Distributions of couplings are presented for two classes of axion reheatons, both of which exhibit very small couplings to most of the gauge sectors. In one class, ratios of reheating couplings and also preferred gauge groups are frequently determined by local regions in the string geometry.

    ↳ hep-thastro-ph.COhep-phPRD(2019)·39 citations
35. 35*

    Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider

    Juliette Alimena (1)🇺🇸 · James Beacham (2)🇺🇸 · Martino Borsato (3)🇩🇪 · Yangyang Cheng (4)🇺🇸 · Xabier Cid Vidal (5)🇪🇸 · Giovanna Cottin (6)🇹🇼 · Albert De Roeck (7)🇨🇭 · Nishita Desai (8)🇮🇳 · David Curtin (9)🇨🇦 · Jared A. Evans (10)🇺🇸 · Simon Knapen (11)🇭🇺 · Sabine Kraml (12)🇫🇷 and 189 other authors

    Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Hadron Collider (LHC) at CERN, these long-lived particles (LLPs) can decay far from the interaction vertex of the primary proton-proton collision. Such LLP signatures are distinct from those of promptly decaying particles that are targeted by the majority of searches for new physics at the LHC, often requiring customized techniques to identify, for example, significantly displaced decay vertices, tracks with atypical properties, and short track segments. Given their non-standard nature, a comprehensive overview of LLP signatures at the LHC is beneficial to ensure that possible avenues of the discovery of new physics are not overlooked. Here we report on the joint work of a community of theorists and experimentalists with the ATLAS, CMS, and LHCb experiments --- as well as those working on dedicated experiments such as MoEDAL, milliQan, MATHUSLA, CODEX-b, and FASER --- to survey the current state of LLP searches at the LHC, and to chart a path for the development of LLP searches into the future, both in the upcoming Run 3 and at the High-Luminosity LHC. The work is organized around the current and future potential capabilities of LHC experiments to generally discover new LLPs, and takes a signature-based approach to surveying classes of models that give rise to LLPs rather than emphasizing any particular theory motivation. We develop a set of simplified models; assess the coverage of current searches; document known, often unexpected backgrounds; explore the capabilities of proposed detector upgrades; provide recommendations for the presentation of search results; and look towards the newest frontiers, namely high-multiplicity "dark showers", highlighting opportunities for expanding the LHC reach for these signals.

    ↳ hep-exhep-phJ.Phys.G(2020)·540 citations
36. 36*

    Multi-wavelength spectroscopy of the black hole candidate MAXI J1813-095 during its discovery outburst

    M. Armas Padilla🇪🇸 · T. Muñoz-Darias🇪🇸 · J. Sánchez-Sierras🇪🇸 · B. De Marco🇵🇱 · F. Jiménez-Ibarra🇪🇸 · J. Casares🇪🇸 · J. M. Corral-Santana🇨🇱 · M. A. P. Torres🇪🇸

    MAXI J1813-095 is an X-ray transient discovered during an outburst in 2018. We report on X-ray and optical observations obtained during this event, which indicate that the source is a new low-mass X-ray binary. The outburst lasted ~70 d and peaked at Lx(0.5-10keV)~7.6 x 10^36 erg s-1, assuming a distance of 8 kpc. Swift/XRT follow-up covering the whole activity period shows that the X-ray emission was always dominated by a hard power-law component with a photon index in the range of 1.4-1.7. These values are consistent with MAXI J1813-095 being in the hard state, in agreement with the ~30 per cent fractional root-mean-square amplitude of the fast variability (0.1-50 Hz) inferred from the only XMM-Newton observation available. The X-ray spectra are well described by a Comptonization emission component plus a soft, thermal component (kT ~0.2 keV), which barely contributes to the total flux (<8 per cent). The Comptonization y-parameter (~1.5), together with the low temperature and small contribution of the soft component supports a black hole accretor. We also performed optical spectroscopy using the VLT and GTC telescopes during outburst and quiescence, respectively. In both cases the spectrum lack emission lines typical of X-ray binaries in outburst. Instead, we detect the Ca II triplet and H_alpha in absorption. The absence of velocity shifts between the two epochs, as well as the evolution of the H_alpha equivalent width, strongly suggest that the optical emission is dominated by an interloper, likely a G-K star. This favours a distance >3 kpc for the X-ray transient.

    ↳ astro-ph.HEhep-phMNRAS(2019)·12 citations
37. 37*

    New CMB spectral distortion constraints on decaying dark matter with full evolution of electromagnetic cascades before recombination

    Sandeep Kumar Acharya🇮🇳 · Rishi Khatri🇮🇳

    Current constraints on energy injection in the form of energetic particles before the epoch of recombination using CMB spectral distortions assume that all energy goes into $y$ and $\mu$-type distortions. We revisit these constraints with exact calculations of the spectral distortions by evolving the electromagnetic cascades. The actual spectral distortion differs in shape and amplitude from the $y$-type distortion and depends on the energy and nature of injected particles. The constraints on the energy injection processes such as dark matter decay can be relaxed by as much as a factor of 5.

    ↳ astro-ph.COastro-ph.HEhep-phPRD(2019)·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.