DOCSLIB.ORG

Dark Matter and the Xenon1t Electron Recoil Excess

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dark Matter and the Xenon1t Electron Recoil Excess Dark Matter and the Xenon1T electron recoil excess Kristjan Kannike, Martti Raidal, and Hardi Veerm¨ae National Institute of Chemical Physics and Biophysics, R¨avala10, Tallinn 10143, Estonia Alessandro Strumia Dipartimento di Fisica dell’Universit`adi Pisa, Italia Daniele Teresi Dipartimento di Fisica dell’Universit`adi Pisa and INFN, Italia (Dated: November 10, 2020) We show that the electron recoil excess around 2 keV claimed by the Xenon collaboration can be fitted by DM or DM-like particles having a fast component with velocity of order ∼ 0:1. Those particles cannot be part of the cold DM halo of our Galaxy, so we speculate about their possible nature and origin, such as fast moving DM sub-haloes, semi-annihilations of DM and relativistic axions produced by a nearby axion star. Feasible new physics scenarios must accommodate exotic DM dynamics and unusual DM properties. INTRODUCTION into account a Maxwellian-like tail of their velocity dis- tribution around or above the cut-off due to the escape The Xenon collaboration reported results of searches velocity from the Milky Way, 0:0015 < vesc < 0:002 [15] for new physics with low-energy electronic recoil data in natural units. As we will see, the Xenon1T excess recorded with the Xenon1T detector [1]. They claim an needs a flux of fast (and possibly even relativistic) parti- excess of events over the known backgrounds in the recoil cles. energy ER range 1-7 keV, peaked around 2.4 keV. The In this work we demonstrate that a flux of fast DM can local statistical significance is around 3-4σ, although part provide a good fit to the Xenon1T excess, and determine of the excess could be due to a small tritium background the necessary flux and velocity. Our results show that in the Xenon1T detector [1]. adding a free tritium abundance to the detector does not The statistical significance of the excess is 3:5σ when improve the fit. We later speculate about possible origins interpreted in terms of axions [2{4] emitted by thermal of such a fast DM component. processes in the Sun. This interpretation, considered by the Xenon collaboration [1], depends on the axion- FAST DM FIT TO XENON1T DATA electron coupling gae, that dominates both the detec- tion and the production in the Sun. Interestingly, the 0 Sun emits such axions in the desired energy range with We consider an elastic DM e ! DM e scattering be- a spectrum that can fit the excess. Although the so- tween a DM particle with initial velocity ~vDM and an lar axion scenario has all the ingredients to explain the electron with initial velocity ~ve that acquires final veloc- 0 anomaly, the needed parameter space is excluded by stel- ity ~ve. Assuming, for simplicity, that they are parallel lar cooling bounds on the axion-electron coupling [5{9]. and non-relativistic, the transferred recoil energy is Indeed, to fit the excess, the Xenon collaboration re- −12 ER ≡ Ee0 − Ee = 2µvrelvCM quires gae ≈ 3:7 · 10 while stellar cooling constraints < −12 2m v (v − v ) for m m ; (1) imply gae 0:3 · 10 . As the Xenon1T rate scales as DM e DM e DM e arXiv:2006.10735v3 [hep-ph] 9 Nov 2020 ∼ ' 4 2mevDM(vDM − ve) for mDM me; gae, bounds from cooling of hotter stars rule out this sce- nario quite convincingly. Neutrinos with a hypothetical and the transferred momentum is magnetic moment are similarly excluded [1, 10]. Parti- 0 cles with small renormalizable interactions are less con- q ≡ mDM(vDM − vDM) = −2µvrel strained by hotter stars [11, 12]. Still, this study demon- 2mDM(vDM − ve) for mDM me; (2) strates the need for a flux of fast particles in order to fit ' − 2me(vDM − ve) for mDM me; the data. Since DM exists, it is interesting to study whether where vCM ≡ (meve + mDMvDM)=(me + mDM) is the the Xenon1T anomaly can be explained in some DM center-of-mass velocity, vrel ≡ vDM − ve is the relative scenario. A narrow peak in the recoil energy ER can velocity, and µ ≡ memDM=(me + mDM) is the reduced be provided by absorption of a light bosonic DM parti- mass. We see that the desired ER ∼ 2:4 keV can be cle [1, 13] or by DM DM e ! DM e semi-absorption [14]. obtained for mDM me with vDM ≈ 0:1 or for mDM Scatterings of DM particles provide a broader structure, me and faster DM, that becomes relativistic for mDM ∼ 2 2 but cold DM particles are too slow, even when taking 0:1me. Notice that ER ' qvCM so that q ≈ (40 keV) . 2 fit both with negligible and free tritium abundance. In ) 100 the latter case, the tritium signal shape is taken from [19] and its magnitude is fitted. 80 Fig.1 compares the Xenon1T data to sample spectra ton yr keV /( of the electron excess, computed for some values of the 60 DM mass and velocity. Fig.2 shows which values of these parameters best fit A:m =1 GeV,v/c= 0.1 40 DM the energy spectrum of the excess. We find that DM m v c B: DM=10 MeV, / = 0.1 heavier than the electron with velocities v ∼ 0:1 fits 20 m v c DM C: DM=3 MeV, / = 0.05 the excess well. On the other hand, lower masses do D:m DM=5 GeV,v/c= 0.01 Binned rate in events 0 not provide sufficiently high electron recoil (unless the 2 4 6 8 10 DM velocity is increased to relativistic values), whereas Electron recoil energy in keV slower DM (even if heavier, to provide sufficient recoil) tends to give a too large signal in the first bin 1{2 keV. Allowing for a free amount of tritium background (dotted FIG. 1. Sample spectra for different values of DM mass contours in fig.2) does not shift significantly the best-fit and velocity. The gray curve is the background claimed by regions because tritium reproduces the energy spectrum (assuming negligible tritium contribution) and the Xenon1T of the excess less well than fast DM. data points are shown in black. Fig.3 shows the values of the number density of the fast DM component times its cross section on elec- We validate the above estimates by performing a de- trons needed to reproduce the excess rate claimed by tailed computation taking into account the Xe atomic Xenon1T. structure, along the lines of [16, 17]. In particular, we We assumed that DM has a velocity distribution use the relativistic wave-functions for the ionization fac- peaked at any given v and constant σe. If the cross sec- tor provided in [17]. tion σe were velocity-dependent, our fit applies with σe For a fixed DM velocity vDM (hereafter denoted by v evaluated at v. If the velocity distribution has a width, to simplify the notation), the differential cross-section is the fit still holds until it exceeds the Xenon energy res- olution. Non-monochromatic velocity distributions pro- Z q+ dσv σe 2 2 duce broader signals. In particular, the required popula- = a0 q dqjF (q)j K(ER; q); (3) dER 2mev q− tion of fast DM particles cannot arise from a high-velocity tail of a broad distribution (e.g. thermal), because such where σe is the free electron cross-section at fixed mo- scenarios would be produce a too strong signal in the mentum transfer q = 1=a0, where a0 = 1=(αme) is the lower energy bin at 1{2 keV. Bohr radius. The limits of integration are q 2 2 q± = mDMv ± mDMv − 2mDMER: (4) DISCUSSION AND SPECULATIONS We assume the DM form factor F (q) = 1 obtained, We have seen that the Xenon1T electron recoil ex- e.g., from heavy mediators. The atomic excitation factor cess can be interpreted as due to a flux of high veloc- K(ER; q) is taken from [18] and includes the relativistic ity particles. Their velocities have to be so high that corrections, relevant at large momentum exchange. For these particles cannot be gravitationally bound to the ER ∼ keV recoil energies, the excitation factor is domi- DM halo of our Galaxy. Here we will speculate about nated by the n = 3 and n = 4 atomic shells, the former possible physical origins of such flux of fast DM-like par- starting at ER > 1:17 keV. The differential rate is given ticles. One needs to consider non-trivial DM dynamics, by that must be consistent with all constraints. For exam- dR dσv ple, DM up-scattering by cosmic rays [20, 21] seems not = nT nDM ; (5) to be consistent with other experiments. dER dER One possibility is that the Earth is currently passing 27 where nT ' 4:2 × 10 =ton is the number density of through a DM (sub-)halo that moves with a very high Xenon atoms, and nDM is the number density of the speed relative to us. The origin of such halo is, however, fast DM component. The rate depends on the product unclear, as the required velocities v >∼ 0:05 are an order of nDMσe, which we fit to the Xenon1T excess. To com- magnitude larger than the velocity dispersions in nearby pare the spectra with the Xenon1T data, we smear them rich galaxy clusters. by a detector resolution σdet = 0:45 keV [19], approxi- Another possibility is that a flux of fast DM is pro- mated as constant, multiply by the efficiency given in [1] duced by semi-annihilation processes (see e.g. [22{28]) and bin them as the available data in [1].
Load more

Recommended publications
  • Measurement of Associated Z+Charm Production and Search for W' Bosons in the CMS Experimented at the LHC
    UNIVERSIDAD COMPLUTENSE DE MADRID FACULTAD DE CIENCIAS FÍSICAS Departamento de Física Atómica, Molecular y Nuclear TESIS DOCTORAL Measurement of associated Z+charm production and search for W' bosons in the CMS experimented at the LHC Medida de la producción asociada de Z+charm y búsqueda de bosones W' en el experimento CMS del LHC MEMORIA PARA OPTAR AL GRADO DE DOCTOR PRESENTADA POR Alberto Escalante del Valle Director Juan Alcaraz Maestre Madrid, 2017 ©Alberto Escalante del Valle, 2017 CENTRO DE INVESTIGACIONES ENERGETICAS´ MEDIOAMBIENTALES Y TECNOLOGICAS´ Measurement of associated Z+charm production and Search for W0 bosons in the CMS experiment at the LHC by Alberto Escalante del Valle A thesis submitted in partial fulfillment for the degree of Doctor of Philosophy in the Universidad Complutense de Madrid Facultad de Ciencias F´ısicas Departamento de F´ısicaAt´omica,Molecular y Nuclear Supervised by: Dr. Juan Alcaraz Maestre Dr. Juan Pablo Fern´andezRamos Madrid February 2017 CENTRO DE INVESTIGACIONES ENERGETICAS´ MEDIOAMBIENTALES Y TECNOLOGICAS´ Medida de la producci´onasociada de Z+charm y B´usquedade bosones W0 en el experimento CMS del LHC por Alberto Escalante del Valle Memoria de la tesis presentada para optar al grado de Doctor en Filosof´ıa en la Universidad Complutense de Madrid Facultad de Ciencias F´ısicas Departamento de F´ısicaAt´omica,Molecular y Nuclear Supervisado por: Dr. Juan Alcaraz Maestre Dr. Juan Pablo Fern´andezRamos Madrid Febrero 2017 Abstract Measurement of associated Z+charm production and Search for W0 bosons in the CMS experiment at the LHC by Alberto Escalante del Valle Do we understand how elementary particles interact with each other? Are we able to predict the result of the collisions of these elementary particles at the LHC? The objective of this thesis is to investigate the validity of our current theoretical model, the Standard Model of particle physics, to explain the production of two low rate processes in proton-proton collisions at the LHC.
    [Show full text]
  • Jhep06(2019)110
    Published for SISSA by Springer Received: February 22, 2019 Revised: June 3, 2019 Accepted: June 10, 2019 Published: June 20, 2019 Coset cosmology JHEP06(2019)110 Luca Di Luzio,a;b Michele Redi,c Alessandro Strumiaa and Daniele Teresia;b aDipartimento di Fisica, Universit`adi Pisa, Largo Pontecorvo 3, I-56127 Pisa, Italy bINFN, Sezione di Pisa, Largo Pontecorvo 3, I-56127 Pisa, Italy cINFN Sezione di Firenze, Via G. Sansone 1, I-50019 Sesto Fiorentino, Italy E-mail: [email protected], [email protected], [email protected], [email protected] Abstract: We show that the potential of Nambu-Goldstone bosons can have two or more local minima e.g. at antipodal positions in the vacuum manifold. This happens in many models of composite Higgs and of composite Dark Matter. Trigonometric potentials lead to unusual features, such as symmetry non-restoration at high temperature. In some mod- els, such as the minimal SO(5)=SO(4) composite Higgs with fermions in the fundamental representation, the two minima are degenerate giving cosmological domain-wall problems. Otherwise, an unusual cosmology arises, that can lead to supermassive primordial black holes; to vacuum or thermal decays; to a high-temperature phase of broken SU(2)L, pos- sibly interesting for baryogenesis. Keywords: Cosmology of Theories beyond the SM, Global Symmetries, Spontaneous Symmetry Breaking, Technicolor and Composite Models ArXiv ePrint: 1902.05933 Open Access, c The Authors. https://doi.org/10.1007/JHEP06(2019)110 Article funded by SCOAP3. Contents
    [Show full text]
  • Phenomenological Implications of Neutrinos in Extra Dimensions
    October 27, 2018 CERN-TH/2001–184 hep-ph/0107156 IFUP–TH/18–2001 Phenomenological implications of neutrinos in extra dimensions Andr´ede Gouvˆea, Gian Francesco Giudice, Alessandro Strumia∗, and Kazuhiro Tobe Theoretical Physics Division, CERN, CH-1211, Gen`eve 23, Switzerland Abstract Standard Model singlet neutrinos propagating in extra dimensions induce small Dirac neutrino masses. While it seems rather unlikely that their Kaluza-Klein excitations directly participate in the observed neutrino oscillations, their virtual exchange may lead to detectable signatures in future neutrino experiments and in rare charged lepton processes. We show how these effects can be described by specific dimension-six effective operators and discuss their experimental signals. 1 Introduction The hypothesis that Standard Model (SM) singlet fields propagate in extra dimensions leads to striking arXiv:hep-ph/0107156v2 1 Nov 2001 results. When applied to the graviton, it allows to lower the quantum gravity scale down to few TeV [1, 2], suggesting a new scenario for addressing the Higgs mass hierarchy problem. It is also natural to consider the case of “right-handed neutrinos” (i.e., fermions without SM gauge interactions) propagating in extra dimensions. The smallness of the neutrino masses, of the Dirac type, could in fact be a manifestation of this hypothesis [3, 4, 5, 6]. If the radius of the compactified dimensions is very large, R > eV−1, Kaluza-Klein (KK) modes of right-handed neutrinos would significantly participate in neutrino∼ oscillations. However, KK interpreta- tions of the atmospheric and solar neutrino puzzles are disfavoured by the following arguments: A KK tower of sterile neutrinos gives rise to active/sterile oscillations at a small ∆m2 1/R2 • ∼ only in the case of a single large extra dimension.
    [Show full text]
  • Higgs Inflation
    Higgs inflation Javier Rubio Institut fur¨ Theoretische Physik, Ruprecht-Karls-Universitat¨ Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany —————————————————————————————————————————— Abstract The properties of the recently discovered Higgs boson together with the absence of new physics at collider experiments allows us to speculate about consistently extending the Standard Model of particle physics all the way up to the Planck scale. In this context, the Standard Model Higgs non- minimally coupled to gravity could be responsible for the symmetry properties of the Universe at large scales and for the generation of the primordial spectrum of curvature perturbations seeding structure formation. We overview the minimalistic Higgs inflation scenario, its predictions, open issues and extensions and discuss its interplay with the possible metastability of the Standard Model vacuum. —————————————————————————————————————————— arXiv:1807.02376v3 [hep-ph] 13 Mar 2019 Email: [email protected] 1 Contents 1 Introduction and summary3 2 General framework7 2.1 Induced gravity . .7 2.2 Higgs inflation from approximate scale invariance . .8 2.3 Tree-level inflationary predictions . 11 3 Effective field theory interpretation 14 3.1 The cutoff scale . 14 3.2 Relation between high- and low-energy parameters . 16 3.3 Potential scenarios and inflationary predictions . 17 3.4 Vacuum metastability and high-temperature effects . 21 4 Variations and extensions 22 4.1 Palatini Higgs inflation . 23 4.2 Higgs-Dilaton model . 24 5 Concluding remarks 26 6 Acknowledgments 26 2 1 Introduction and summary Inflation is nowadays a well-established paradigm [1–6] able to explain the flatness, homogene- ity and isotropy of the Universe and the generation of the primordial density fluctuations seeding structure formation [7–10].
    [Show full text]
  • Astrophysics and Physics of Neutrino Detection
    Astrophysics and Physics of Neutrino Detection A THESIS SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY Cheng-Hsien Li IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Doctor of Philosophy Professor Yong-Zhong Qian, Advisor September, 2017 c Cheng-Hsien Li 2017 ALL RIGHTS RESERVED Acknowledgements This dissertation would be impossible to complete without the help and support from many people and institutions. First and foremost, I would like to express my sincere gratitude to my research advisor, Professor Yong-Zhong Qian, who has patiently guided me through this long PhD journey. I learned a lot from his insights in neutrino physics and his approaches to problems during countless hours of discussion. He always offered helpful suggestions regarding my thesis projects and how to conduct rigorous research. I would like to thank Dr. Projjwal Banerjee for guiding me on the SN1987A project presented in this thesis. He was not only a research collaborator but he is also a dear friend to me. He kindly offered advice and encouragement which helped me overcome difficulties during my PhD study. In addition, I feel grateful to have received a lot of help from then fellow graduate students, Dr. Ke-Jun Chen, Dr. Meng-Ru Wu, Dr. Zhen Yuan, Mr. Zhu Li, and Mr. Zewei Xiong, in the Nuclear Physics Group. I am also indebted to Professor Hans-Thomas Janka and Professor Tobias Fischer for generously providing supernova simulation results from their research groups upon request, Professor Huaiyu Duan for commenting on my wave-packet project, and Professor Alexander Heger for the computing resource I received in the research group.
    [Show full text]
  • Indirect Searches in the PAMELA and Fermi Era Aldo Morselli, Igor Moskalenko
    Indirect searches in the PAMELA and Fermi era Aldo Morselli INFN, Sezione di Roma Tor Vergata Springel, Wang, Volgensberger, Ludlow, Jenkins, Helmi, Navarro, Frenk & White ‘08 New Horizons for Modern Cosmology, Dark Matter, February 9, 2009, Galileo Instiute, Firen Aldo Morselli, INFN Roma Tor Vergata 1 PAMELA: Cosmic-Ray Antiparticle Measurements: Antiprotons an example in mSUGRA 5 years simulation fd: Clumpiness factors needed to disentangle a neutralino induced component in the antiproton flux f = the dark matter fraction concentrated in clumps d = the overdensity due to a clump with respect to the local halo density A.Lionetto, A.Morselli, V.Zdravkovic JCAP09(2005)010 [astro-ph/0502406] New Horizons for Modern Cosmology, Dark Matter, February 9, 2009, Galileo Instiute, Firen Aldo Morselli, INFN Roma Tor Vergata 2 Supersymmetry introduces free parameters: In the MSSM, with Grand Unification assumptions, the masses and couplings of the SUSY particles as well as their production cross sections, are entirely described once 5 parameters are fixed: • M1/2 the mass parameter of supersymmetric partners of gauge fields (gauginos) • µ the higgs mixing parameters that appears in the neutralino and chargino mass matrices • m0 the common mass for scalar fermions at the GUT scale • A the trilinear coupling in the Higgs sector • tang β = v2 / v1 = <H2> / <H1> the ratio between the two vacuum expectation values of the Higgs fields New Horizons for Modern Cosmology, Dark Matter, February 9, 2009, Galileo Instiute, Firen Aldo Morselli, INFN Roma Tor Vergata
    [Show full text]
  • Sterile Neutrinos in 4D and 5D in Supernovæ and the Cosmo
    Scuola Normale Superiore Sterile Neutrinos in 4D and 5D in Supernovæ and the Cosmo Marco Cirelli Advisors Dr. Andrea Romanino Prof. Riccardo Barbieri Ph.D. Thesis Autumn 2003 A Anna Contents Preface iii Rationale 1 1 Introduction: New Particle Physics from Astrophysics and Cosmology 3 1.1 TheStandardModelandwhytogobeyond . ......... 3 1.1.1 TheHierarchyProblem . ..... 5 1.1.2 Introduction to Extra Dimensions . ......... 7 1.2 “Standard” neutrino physics and why to go beyond . .............. 11 1.2.1 “Whatisleft,whatisnext?” . ....... 13 1.2.2 Sterileneutrinos .............................. ...... 15 1.3 TheroleofSupernovæ.............................. ....... 18 1.3.1 Supernova basics and neutrino signal formation . .............. 18 1.3.2 Theenergylossconstraint. ........ 21 1.3.3 Waitingforthenextsupernova . ........ 23 1.4 TheroleoftheEarlyUniverse . ......... 27 1.4.1 Big Bang Nucleosynthesis . ....... 27 1.4.2 Large Scale Structure and Cosmic Microwave Background............. 35 2 A (4D) sterile neutrino 38 2.1 Active-sterile neutrino mixing formalism . ................ 38 2.2 Sterile effects in cosmology . .......... 41 2.2.1 Technicaldetails .............................. ...... 41 2.2.2 Results ....................................... 45 2.3 SterileeffectsinSupernovæ . .......... 48 2.3.1 Technicaldetails .............................. ...... 50 2.3.2 Results ....................................... 54 3 Neutrinos in Extra Dimensions 56 3.1 Theextradimensionalsetup. .......... 57 3.2 Cosmological safety (or irrelevance) . ............... 58 i 3.3 Supernovacoreevolution . ......... 58 3.3.1 Thefeedbackmechanisms . ...... 59 3.3.2 Details of the model of core evolution . .......... 60 3.4 Theoutcome: boundsandsignals. .......... 70 3.5 Appendix: subleading invisible channels . ............... 76 4 Conclusions 77 References 79 ii Preface During my Ph.D. course, under the guidance of Riccardo Barbieri and Andrea Romanino, I began work- ing on fascinating subjects at the intersection of High Energy Physics, Neutrino Physics, Astrophysics and Cosmology.
    [Show full text]
  • Pos (EPS-HEP2011) 098 Neutrino Mass Models at the Tev Scale
    Neutrino mass models at the TeV scale and their PoS(EPS-HEP2011)098 tests at the LHC Alessandro Strumia∗ Dipartimento di Fisica dell’Università di Pisa and INFN, Italia National Institute of Chemical Physics and Biophysics, Ravala 10, Tallinn, Estonia E-mail: [email protected] Assuming that the new particles introduced by type-I, type-II, type-III see-saw in order to mediate neutrino masses are below a TeV, we describe their resulting manifestations at LHC. The 2011 Europhysics Conference on High Energy Physics-HEP 2011, July 21-27, 2011 Grenoble, Rhône-Alpes France ∗Speaker. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/ Neutrino mass models at LHC Alessandro Strumia HH HH L H Singlet Triplet Triplet LL LL L H Figure 1: The neutrino Majorana mass operator (LH)2 can be mediated by tree level exchange of: I) a fermion singlet (‘see-saw’); II) a fermion triplet; III) a scalar triplet. PoS(EPS-HEP2011)098 1. See-saw models In the past decade we observed violations of lepton flavor in neutrinos and understood that it is due to neutrino oscillations due to neutrino masses [1]. Neutrino masses can be of Majorana type (violating also lepton number) or of Dirac type (adding to the SM a light right-handed neutrino, such that lepton number is conserved). We here stick to the most plausible scenario for neutrino masses: the see-saw models, all de- signed to give at tree level Majorana masses described by the unique dimension-5 effective operator 2 2 (LH) =2LL.
    [Show full text]
  • Jhep06(2010)036
    Published for SISSA by Springer Received: April 6, 2010 Accepted: May 25, 2010 Published: June 8, 2010 JHEP06(2010)036 Thermal production of axino dark matter Alessandro Strumia CERN, PH-TH, CH-1211, Geneva 23, Switzerland Dipartimento di Fisica dell’Universit`adi Pisa, Largo Pontecorvo 3, 56127, Pisa, Italia INFN { Sezione di Pisa, Largo Pontecorvo 3, 56127, Pisa, Italia E-mail: [email protected] Abstract: We reconsider thermal production of axinos in the early universe, adding: a) missed terms in the axino interaction; b) production via gluon decays kinematically allowed by thermal masses; c) a precise modeling of reheating. We find an axino abunance a few times larger than previous computations. Keywords: Supersymmetry Phenomenology ArXiv ePrint: 1003.5847 Open Access doi:10.1007/JHEP06(2010)036 Contents 1 Introduction1 2 Axino couplings2 3 Thermal axino production rate2 JHEP06(2010)036 4 Thermal axino abundance5 5 Conclusions6 1 Introduction The strong CP problem can be solved by the Peccei-Quinn symmetry [1], that manifests 9 at low energy as a light axion a with a decay constant f >∼ 5 10 GeV [2]. In supersym- metric models the axion a gets extended into an axion supermultiplet which also contains the scalar saxion s and the fermionic axinoa ~ [3{5]. Depending on the model of super- symmetry breaking, the axino can easily be lighter than all other sparticles, becoming the stable lightest supersymmetric particle (LSP) and consequently a Dark Matter candidate (warm axino: [6]; hot axino: [7]; cold axino: [8]; [9]). It is thereby interesting to compute its cosmological abundance.
    [Show full text]
  • KEK-PH2018 Timetable
    KEK-PH2018 Timetable Tuesday, 13 February 2018 09:00 - 09:30 Registration 09:30 - 10:30 Talks Convener: Mihoko Nojiri (KEK) 09:30 Late-time magnetogenesis 30' Speaker: Kiwoon Choi (CTPU, IBS) 10:00 Lovely phase space 30' Speaker: Tom Melia (Kavli IPMU) 10:30 - 11:00 Tea Time 11:00 - 12:00 Talks Convener: Alejandro Ibarra (Technical University of Munich) 11:00 Axion coupled to hidden sector 30' Speaker: Fuminobu Takahashi (Tohoku University) 11:30 Multi-Messenger Astrophysics in the Gravitational Wave Era 30' Speaker: Kunihito Ioka (YITP, Kyoto University) 12:00 - 13:30 Lunch 13:30 - 15:30 Joint Session with Muon g-2 Workshop Convener: Bradley Lee Roberts (Boston University) Location: Kobayashi Hall, Kenkyu-honkan 13:30 Belle II overview 30' Speaker: Phillip Urquijo (University of Melbourne) 14:00 Fermilab muon g-2 experiment 30' Speaker: Sudeshna Ganguly (University of Illinois at Urbana-Champaign) 14:30 J-PARC muon g-2 experiment 30' Speaker: Takayuki Yamazaki (KEK) 15:00 New Physics and the Muon g-2 30' Speaker: Hooman Davoudiasl (Brookhaven National Laboratory) 15:30 - 15:50 Tea Time 15:50 - 17:30 Short Talks Convener: Fuminobu Takahashi (Tohoku University) 15:50 High-energy neutrinos from multi-body decaying dark matter 20' Speaker: Nagisa Hiroshima (KEK, ICRR) 16:10 Search for New physics with High multiplicity from High energy cosmic rays 20' Speaker: Yongsoo Jho (Yonsei University) 16:30 Thermal Gravitational Contribution to Dark Matter Production 20' Speaker: Yong Tang (University of Tokyo) 16:50 Enhanced Axion-Photon Coupling
    [Show full text]
  • Publications 2008- 2009
    Publications 2008- 2009 Inter-team papers – in refereed journals 1. Model-independent implications of the e+-, anti-proton cosmic ray spectra on properties of Dark Matter Marco Cirelli (Saclay, SPhT), Mario Kadastik, Martti Raidal (NICPB, Tallinn), Alessandro Strumia (Pisa U. & INFN, Pisa) . Sep 2008. 25pp. Published in Nucl.Phys.B813:1-21,2009. e-Print: arXiv:0809.2409 [hep-ph]* Cited 141 times 2. Non-linear isocurvature perturbations and non-Gaussianities David Langlois, Filippo Vernizzi, David Wands (includes UniverseNet members from Saclay + APC Paris). Sep 2008. 24pp. Published in JCAP 0812:004,2008. e-Print: arXiv:0809.4646 [astro-ph] Cited 13 times 3. The Effective Theory of Quintessence: the w<-1 Side Unveiled Paolo Creminelli, Guido D'Amico, Jorge Norena, Filippo Vernizzi (includes UniverseNet members from Saclay + ICTP Trieste). Nov 2008. 34pp. Published in JCAP 0902:018,2009. e-Print: arXiv:0811.0827 [astro-ph] Cited 8 times 4. Parameterizing the effect of dark energy perturbations on the growth of structures. Guillermo Ballesteros (Madrid, IFT & CERN), Antonio Riotto (CERN & INFN, Padua). Jul 2008. Published in Phys.Lett.B668:171-176,2008. e-Print: arXiv:0807.3343 [astro-ph]* Cited 11 times 5. Exact Spherically symmetric solutions in massive gravity. Z. Berezhiani (L'Aquila U. & Gran Sasso), D. Comelli (INFN, Ferrara), F. Nesti, L. Pilo (L'Aquila U. & Gran Sasso) . Mar 2008. 20pp. Published in JHEP 0807:130,2008. e-Print: arXiv:0803.1687 [hep-th]* Cited 10 times 6. Precision studies of the NNLO DGLAP evolution at the LHC with CANDIA. Alessandro Cafarella (Democritos Nucl. Res. Ctr.), Claudio Coriano (Salento U.
    [Show full text]
  • Grand Unification at the Electroweak Scale
    Large Extra Dimensions & Grand Unification at the Electroweak Scale Behrad Taghavi Department of Physics & Astronomy, Stony Brook University. ! Advisor: Dr. Patric Meade OUTLINE • Motivations • Kaluza-Klein Theory • Localization on Topological Defects • Large Extra Dimensions Paradigm • ADD Model • Hierarchy Problem • Proton Stability • Other Models (eg. UED) • References 2 MOTIVATIONS We need beyond standard model theories to answer questions like hierarchy problem, unification of all fundamental forces, etc. Most of beyond standard model theories (like String Theory, M Theory, GUTs, MSSM, etc.) predict unification of forces at the energy scale close to planck mass. Large Extra Dimensions paradigm is capable of answering most of unanswered questions in SM elegantly and also keeps high energy physics as a experiment-based field of physics. 3 KALUZA-KLEIN THEORY Kaluza–Klein theory (KK theory) is a unified field theory of gravitation and electromagnetism built around the idea of a fifth dimension beyond the usual 4 of space and time. “Kaluza-Klein” mechanism has been first introduced in the 1921 paper of “Theodor Kaluza” , which extended classical GR to 4+1 dimensions that resulted in unification of Electromagnetism and Einstein’s Gravity. In 1926, “Oskar Klein” gave Kaluza's classical 5-dimensional theory a quantum interpretation by introduction of “curled up” or “compact” dimensions. 4 KALUZA-KLEIN THEORY Assume that the world is (4+ n )-dimensional (n 1 ), but the extra ≥ dimensions are compact. If n =1 , our world is a M 4 S 1 manifold. ! ⌦ All fields are defined on this “M 4 S 1 cylinder”. ⌦ ! For a scalar field Φ ( x µ ,Z ) single-valuedness condition reads: Φ(xµ,Z)=Φ(xµ,Z+2⇡R),µ=0, 1, 2, 3.
    [Show full text]