季向東，張新民，諶勛

·推薦論文摘要·

中國(guó)暗物質(zhì)與暗能量研究5～10年展望

季向東，張新民，諶勛

暗物質(zhì)和暗能量的研究是當(dāng)前基礎(chǔ)物理研究最前沿的方向之一，突破性的重要進(jìn)展將極大促進(jìn)我們對(duì)物質(zhì)世界的微觀結(jié)構(gòu)以及宇宙演化的理解。國(guó)際上對(duì)暗物質(zhì)及暗能量的研究都極為重視，美國(guó)和歐洲多國(guó)都為其進(jìn)行了詳細(xì)周密的規(guī)劃，開(kāi)展了一系列的相關(guān)項(xiàng)目投資。國(guó)內(nèi)也將這方面的研究納入了中長(zhǎng)期規(guī)劃，并認(rèn)為其很可能在不久的將來(lái)實(shí)現(xiàn)革命性的突破。在過(guò)去的幾年內(nèi)，我國(guó)在暗物質(zhì)直接探測(cè)方面實(shí)現(xiàn)了長(zhǎng)足的進(jìn)步，探測(cè)結(jié)果的靈敏度達(dá)到世界先進(jìn)水平。在2015年7月的香山科學(xué)會(huì)議上，一批從事這方面科研以及一批感興趣的科學(xué)家討論了未來(lái)5～10年我國(guó)在暗物質(zhì)暗能量研究方面可能的規(guī)劃和布局，建議依托錦屏地下實(shí)驗(yàn)室進(jìn)行更大規(guī)模的暗物質(zhì)直接探測(cè)實(shí)驗(yàn)，并開(kāi)展衛(wèi)星暗物質(zhì)間接探測(cè)實(shí)驗(yàn)，力爭(zhēng)在暗物質(zhì)研究方面達(dá)到世界領(lǐng)先水平。同時(shí)建議在西藏阿里地區(qū)進(jìn)行宇宙微波背景輻射觀測(cè)，并通過(guò)空間站和地面望遠(yuǎn)鏡進(jìn)行深空巡天觀測(cè)，從而實(shí)現(xiàn)對(duì)暗能量的深入研究。

暗物質(zhì)；暗能量；地下實(shí)驗(yàn)室；宇宙微波背景輻射

來(lái)源出版物：科學(xué)通報(bào), 2016(11): 1181-1187

聯(lián)系郵箱：諶勛，chenxun@sjtu.edu.cn

基于地下實(shí)驗(yàn)室的暗物質(zhì)直接探測(cè)實(shí)驗(yàn)

趙偉，程建平，岳騫

摘要：暗物質(zhì)研究是當(dāng)前基礎(chǔ)物理研究的前沿?zé)狳c(diǎn)課題之一，對(duì)天體物理學(xué)、宇宙學(xué)和粒子物理學(xué)等學(xué)科的發(fā)展具有十分重要的意義。暗物質(zhì)的直接探測(cè)實(shí)驗(yàn)是進(jìn)行暗物質(zhì)研究的手段之一，也被認(rèn)為是最為重要的一種方法。本文介紹：暗物質(zhì)的不同探測(cè)方法、暗物質(zhì)直接探測(cè)實(shí)驗(yàn)的原理；國(guó)際上主要的地下實(shí)驗(yàn)室、針對(duì)輕質(zhì)量和重質(zhì)量暗物質(zhì)進(jìn)行直接探測(cè)的典型實(shí)驗(yàn)及目前取得的進(jìn)展；下一代實(shí)驗(yàn)將面臨的挑戰(zhàn)和機(jī)遇。

關(guān)鍵詞：輕質(zhì)量暗物質(zhì)；重質(zhì)量暗物質(zhì)；直接探測(cè)；地下實(shí)驗(yàn)室

來(lái)源出版物：科技導(dǎo)報(bào), 2016, 34(5): 26-31

聯(lián)系郵箱：趙偉，w-zhao11@mail.tsinghua.edu.cn

關(guān)于“暗物質(zhì)”的猜測(cè)（宇宙兩暗問(wèn)題探索之二）

徐麗琴，徐來(lái)自，張雪峰，等

摘要：星系的平直型旋轉(zhuǎn)曲線以及引力透鏡效應(yīng)觀測(cè)結(jié)果暗示暗物質(zhì)的存在，但迄今還不知道暗物質(zhì)是什么。有文獻(xiàn)曾提出，這種旋轉(zhuǎn)曲線表明暗物質(zhì)是星系所發(fā)射的穩(wěn)定、各向同性能量流；在此基礎(chǔ)上，本文提出猜測(cè)：這種能量流的主要成分是電磁輻射，并以星系核的表面亮度與遠(yuǎn)離星系核的旋轉(zhuǎn)速度的關(guān)系證實(shí)了這個(gè)猜測(cè)。根據(jù)這個(gè)猜測(cè)解釋了太陽(yáng)系的旋轉(zhuǎn)曲線為何呈現(xiàn)開(kāi)普勒型，還解釋了1E 0657-56星系團(tuán)觀測(cè)結(jié)果所顯示的現(xiàn)象。根據(jù)這個(gè)猜測(cè)還能夠解釋令天文學(xué)家感到困惑的異?，F(xiàn)象：大部分星系旋轉(zhuǎn)曲線呈現(xiàn)平直型，而NGC4736星系、NGC3521星系以及NGC4258星系中心黑洞等等的旋轉(zhuǎn)曲線為何呈現(xiàn)開(kāi)普勒型。

關(guān)鍵詞：暗物質(zhì)；旋轉(zhuǎn)曲線；電磁輻射；表面亮度

來(lái)源出版物：內(nèi)蒙古科技大學(xué)學(xué)報(bào), 2016, 35(1): 1-7

關(guān)于宇宙暗物質(zhì)主要形態(tài)之黑洞-夸克星的

新證據(jù)分析

張海鵬，張力，羅延安，等

摘要：通過(guò)分析新近證據(jù)，進(jìn)一步探討宇宙暗物質(zhì)等問(wèn)題，分析認(rèn)為：1）宇宙紫外輻射超出已知輻射源4倍的發(fā)現(xiàn)，可能就是源于我國(guó)的、2013年初預(yù)言的約在可見(jiàn)光附近波段的宇宙背景輻射；彭羅斯等2010年發(fā)現(xiàn)的CMB偏振環(huán)等新證據(jù)，較有力地支持原始夸克星碰撞、重組的宇宙演化及起源模型；黑洞（暗星）-夸克星可能是宇宙暗物質(zhì)的主要形態(tài)，應(yīng)足以解釋暗物質(zhì)與可見(jiàn)物質(zhì)的比例。以上均應(yīng)深入研究；2）76個(gè)黑洞的強(qiáng)大磁場(chǎng)的發(fā)現(xiàn)，客觀上有力地支持了星系中心超大質(zhì)量黑洞等的攜1/3正負(fù)電子電荷的最基本的正、負(fù)夸克構(gòu)型；3）質(zhì)能守恒定律的經(jīng)典物理學(xué)意義所推論的最基本夸克的空心圈環(huán)結(jié)構(gòu)，為圈量子引力奠定了較堅(jiān)實(shí)的粒子物理學(xué)基礎(chǔ)；4）結(jié)合高頻引力波產(chǎn)生機(jī)理（激光約束核聚變等）及探測(cè)機(jī)理，應(yīng)對(duì)中微子與高頻引力波（引力子）進(jìn)行會(huì)師研究。

關(guān)鍵詞：黑洞；暗星；夸克星；圈量子引力；引力波；

高頻；中微子；左旋；暗物質(zhì)

來(lái)源出版物：山西師范大學(xué)學(xué)報(bào): 自然科學(xué)版, 2015, 29(2): 49-54

暗物質(zhì)粒子探測(cè)衛(wèi)星及鄰近的電子宇宙射線源

常進(jìn)，馮磊，郭建華，等

摘要：在中國(guó)科學(xué)院空間科學(xué)戰(zhàn)略性先導(dǎo)科技專項(xiàng)的支持下，紫金山天文臺(tái)等單位正在建造“暗物質(zhì)粒子探測(cè)衛(wèi)星”（DAMPE），預(yù)期將于2015年底發(fā)射升空。暗物質(zhì)粒子探測(cè)衛(wèi)星是一個(gè)高能伽瑪射線、宇宙線探測(cè)器，有望在1～10 TeV的電子宇宙射線能譜測(cè)量以及GeV-TeV伽瑪射線線譜搜尋方面取得重要進(jìn)展。在本文中，我們扼要介紹暗物質(zhì)粒子探測(cè)衛(wèi)星探測(cè)器的主要組成及功能，并介紹紫金山天文臺(tái)的科學(xué)組在鄰近電子宇宙射線源方面的研究進(jìn)展。

關(guān)鍵詞：暗物質(zhì)；宇宙線；空間天文

來(lái)源出版物：中國(guó)科學(xué)：物理學(xué) 力學(xué) 天文學(xué), 2015, 45(11): 119510

聯(lián)系郵箱：常進(jìn)，chang@pmo.ac.cn

天文學(xué)中的暗物質(zhì)和暗能量問(wèn)題之由來(lái)和困惑

武向平

摘要：宇宙起源今天的宇宙學(xué)研究早已經(jīng)沖破了“九重天”的空間尺度和“七天創(chuàng)世紀(jì)”的宗教信仰，21世紀(jì)的宇宙學(xué)已經(jīng)是最精密的自然科學(xué)之一。為現(xiàn)代宇宙學(xué)研究帶來(lái)革命性進(jìn)展的天文學(xué)家無(wú)疑是哈勃，他在1929年發(fā)現(xiàn)了銀河系周圍星系的退行速度與其相距銀河系之距離成正比。此觀測(cè)事實(shí)給了后來(lái)的物理學(xué)家伽莫夫以啟示：既然所有的星系都彼此相互遠(yuǎn)離，那么若沿著時(shí)間的長(zhǎng)河逆向追溯，它們就必將在有限的時(shí)間里匯聚在一起；反之，若沿著時(shí)間發(fā)展的箭頭，宇宙則就像發(fā)生過(guò)一次爆炸一樣，從致密高溫的狀態(tài)膨脹散開(kāi)。

來(lái)源出版物：物理, 2015, 44(06): 411-417

聯(lián)系郵箱：武向平，wxp@bao.ac.cn

中國(guó)暗物質(zhì)實(shí)驗(yàn)（CDEX）合作組研究進(jìn)展

趙偉，岳騫，李金

摘要：暗物質(zhì)是當(dāng)今物理學(xué)最基本也是最吸引人的前沿研究課題之一，對(duì)認(rèn)識(shí)宇宙起源、演變和結(jié)構(gòu)以及物質(zhì)的本源等基本科學(xué)問(wèn)題具有十分重要的意義。暗物質(zhì)的理論研究和實(shí)驗(yàn)探測(cè)經(jīng)過(guò)幾十年的積累和發(fā)展已經(jīng)取得了長(zhǎng)遠(yuǎn)的進(jìn)步。實(shí)驗(yàn)上有多種方法可以進(jìn)行暗物質(zhì)粒子的探測(cè)，直接探測(cè)是一種非常重要的手段。本文評(píng)述了暗物質(zhì)直接探測(cè)方法的原理和當(dāng)今國(guó)際國(guó)內(nèi)采用直接探測(cè)法的不同實(shí)驗(yàn)的研究現(xiàn)狀，著重介紹了中國(guó)暗物質(zhì)實(shí)驗(yàn)（China Dark matter Experiment，CDEX）合作組的研究歷程、探測(cè)技術(shù)和數(shù)據(jù)分析方法、以及研究取得的重要成果和未來(lái)規(guī)劃。

關(guān)鍵詞：暗物質(zhì)；直接探測(cè)；中國(guó)暗物質(zhì)實(shí)驗(yàn)；點(diǎn)電極高純鍺探測(cè)器

來(lái)源出版物：科學(xué)通報(bào), 2015 (25): 2376-2386

聯(lián)系郵箱：岳騫，yueq@mail.tsinghua.edu.cn

暗物質(zhì)粒子探測(cè)器觸發(fā)邏輯測(cè)試系統(tǒng)的設(shè)計(jì)和實(shí)現(xiàn)

張磊，郭建華，張永強(qiáng)

摘要：作為暗物質(zhì)粒子探測(cè)器（DAMPE，Dark Matter Particle Explorer）的一部分，觸發(fā)系統(tǒng)主要用于判選所需探測(cè)的目標(biāo)粒子（高能電子和伽瑪射線）事例，剔除非目標(biāo)粒子事例。觸發(fā)系統(tǒng)由觸發(fā)探測(cè)器和觸發(fā)判選邏輯電路組成。介紹了觸發(fā)地檢測(cè)試系統(tǒng)和宇宙線觸發(fā)系統(tǒng)的設(shè)計(jì)和功能實(shí)現(xiàn)。觸發(fā)地檢系統(tǒng)實(shí)現(xiàn)了對(duì)觸發(fā)判選邏輯電路的電子學(xué)驗(yàn)證；另外，配合宇宙線觸發(fā)系統(tǒng)對(duì)部分觸發(fā)邏輯和觸發(fā)效率進(jìn)行了測(cè)試。主要介紹了觸發(fā)系統(tǒng)的測(cè)試方法和一些初步測(cè)試結(jié)果。

關(guān)鍵詞：儀器：探測(cè)器；暗物質(zhì)；方法：實(shí)驗(yàn)室

來(lái)源出版物：天文學(xué)報(bào), 2014, 55(6): 522-533

聯(lián)系郵箱：張磊，zhanglei@pmo.ac.cn

暗宇宙之暗物質(zhì)研究進(jìn)展

盧瑜，孟曉磊，張同杰

摘要：對(duì)暗物質(zhì)研究進(jìn)行了系統(tǒng)性的綜述。從標(biāo)準(zhǔn)宇宙學(xué)模型出發(fā)，討論了暗物質(zhì)研究的歷史、暗物質(zhì)的分類、暗物質(zhì)的候選者（包括重子暗物質(zhì)與非重子暗物質(zhì)候選者）、暗物質(zhì)的理論模型、暗物質(zhì)的探測(cè)方法和暗物質(zhì)對(duì)宇宙演化的影響。最后，我們對(duì)暗物質(zhì)研究做了總結(jié)和展望。

關(guān)鍵詞：暗物質(zhì)；宇宙學(xué)；粒子物理

來(lái)源出版物：北京師范大學(xué)學(xué)報(bào)（自然科學(xué)版）, 2014, 2: 142-153

探索上帝粒子與質(zhì)量起源

何紅建，鄺宇平

摘要：歐洲大型強(qiáng)子對(duì)撞機(jī)（LHC）上發(fā)現(xiàn)的125 GeV新希格斯粒子可能成為標(biāo)準(zhǔn)模型預(yù)期的“上帝粒子”。這一革命性發(fā)現(xiàn)開(kāi)啟了探索宇宙中一切基本粒子質(zhì)量起源的新時(shí)代，成為21世紀(jì)粒子物理學(xué)的轉(zhuǎn)折點(diǎn)。文章著重介紹：1）探尋上帝粒子的重大科學(xué)意義；2）探索質(zhì)量起源的歷史，以及為什么牛頓力學(xué)和愛(ài)因斯坦相對(duì)論均未解決質(zhì)量起源問(wèn)題；3）神秘的真空與希格斯機(jī)制；4）上帝粒子是如何提出的和怎樣在LHC上發(fā)現(xiàn)的；5）展望21世紀(jì)質(zhì)量起源的探索與新物理定律的革命。

關(guān)鍵詞：上帝粒子；質(zhì)量起源；對(duì)稱性破缺與希格斯機(jī)制；LHC；高能對(duì)撞機(jī)；新物理探測(cè)；暗物質(zhì)

來(lái)源出版物：物理, 2014, 43(01): 12-24

聯(lián)系郵箱：何紅建，hjhe@tsinghua.edu.cn

來(lái)源出版物：Physics Letters B, 2016, 755: 426-432

聯(lián)系郵箱：Arcadi, G; giorgio.arcadi@th.u-psud.fr

The characterization of the gamma-ray signal from the central Milky Way: A case for annihilating dark matter

Daylan, T; Finkbeiner, DP; Hooper, D; et al.

Abstract:Past studies have identified a spatially extended excess of similar to 1-3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark matter. We revisit and scrutinize this signal with the intention of further constraining its characteristics and origin. By applying cuts to the Fermi event parameter CTBCORE, we suppress the tails of the point spread function and generate high resolution gamma-ray maps, enabling us to more easily separate the various gamma-ray components. Within these maps, we find the GeV excess to be robust and highly statistically significant, with a spectrum, angular distribution, and overall normalization that is in good agreement with that predicted by simple annihilating dark matter models. For example, the signal is very well fit by a 36-51 GeV dark matter particle annihilating to b (b) over bar with an annihilation cross section of sigmav= (1-3) × 10-26cm3/s (normalized to a local dark matter density of 0.4 GeV/cm3). Furthermore, we confirm that the angular distribution of the excess is approximately spherically symmetric and centered around the dynamical center of the Milky Way (within similar to 0.05 degrees of Sgr A*), showing no sign of elongation along the Galactic Plane. The signal is observed to extend to at least similar or equal to 10 degrees from the Galactic Center, which together with its other morphological traits disfavors the possibility that this emission originates from previously known or modeled pulsar populations.

關(guān)鍵詞：dark matter; indirect detection; gamma-rays

來(lái)源出版物：Physics of the Dark Universe, 2016, 12: 1-23

聯(lián)系郵箱：Linden, T; linden.70@osu.edu

The diphoton resonance as a gravity mediator of dark matter

Han, CC; Lee, HM; Park, M; et al.

Abstract:We consider the possibility of interpreting the recently reported diphoton excess at 750 GeV as a spin-two massive particle (such as a Kaluza-Klein graviton in warped extra-dimensions) which serves as a mediator to Dark Matter via its gravitational couplings to the dark sector and to the Standard Model (SM). We model non-universal couplings of the resonance to gauge bosons in the SM and to Dark Matter as a function on their localization in the extra dimension. We find that scalar, fermion or vector dark matter can saturate the dark matter relic density by the annihilation of dark matter into a pair of the SM particles or heavy resonances, in agreement with the diphoton resonance signal strength. We check the compatibility of our hypothesis with other searches for the KK graviton. We show that the invisible decay rate of theresonance into a pair of dark matter is subdominant in the region of the correct relic density, hence leading to no constraints from the mono-jet bound at 8 TeV via the gluon coupling. We also discuss the kinematic features of the decay products of a KK graviton to distinguish the KK graviton from the SM backgrounds or a scalar particle interpretation of the diphoton resonance.

來(lái)源出版物：Physics Letters B, 2016, 755: 371-379

聯(lián)系郵箱：Lee, HM; chengcheng.han@ipmu.jp

The 750 GeV diphoton excess at the LHC and dark matter constraints

Bi, XJ; Xiang, QF; Yin, PF; et al.

Abstract:The recent reported 750 GeV diphoton excess at the 13 TeV LHC is explained in the framework of effective field theory assuming the diphoton resonance is a scalar (pseudoscalar) particle. It is found that the large production rate and the broad width of this resonance are hard to be simultaneously explained if only visible final states are considered. Therefore an invisible decay channel to dark matter (DM) is strongly favored by the diphoton resonance with a broad width, given a large coupling of the new scalar to DM. We set constraints on the parameter space in this scenario using the results from LHC Run 1, DM relic density, and DM direct and indirect detection experiments. We find that the DM searches can exclude a large portion of the parameter regions accounting for the diphoton excess with a broad width.

來(lái)源出版物：Nuclear Physics B, 2016, 909: 43-64

聯(lián)系郵箱：Yin, PF; bixj@ihep.ac.cn

Searching for dark matter annihilation from Milky Way dwarf spheroidal galaxies with six years of Fermi Large Area Telescope data

Ackermann, M; Albert, A; Anderson, B; et al.

Abstract:The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. These constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass?100 GeVannihilating via quark and τ-lepton channels.

來(lái)源出版物：Physical Review Letters, 2015, 115(23): 231301

聯(lián)系郵箱：Ackermann, M; brandon.anderson@fysik.su.se

A tale of tails: Dark matter interpretations of the Fermi GeV excess in light of background model systematics

Calore, F; Cholis, I; McCabe, C; et al.

Abstract:Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with theFermiLarge Area Telescope. This excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Caloreet al.2014. We find that a much larger number of DM models fits the gamma-ray data than previously noted. In particular: (1) In the case of DM annihilation intob, we find that even large DM masses up to mχ?74 GeV are allowed atp-value＞0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from μ+μ-with mχ～60-70 GeV can also account for the excess at higher latitudes, |b|＞2°, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. Finally, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.

來(lái)源出版物：Physical Review D, 2015, 91(6): 063003

聯(lián)系郵箱：Calore, F; f.calore@uva.nl

Dark matter with pseudoscalar-mediated interactions explains the DAMA signal and the galactic center excess

Arina, C; Del Nobile, E; Panci, P

Abstract:We study a Dirac dark matter particle interacting with ordinary matter via the exchange of a light pseudoscalar, and analyze its impact on both direct and indirect detection experiments. We show that this candidate can accommodate the long-standing DAMA modulated signal and yet be compatible with all exclusion limits at 99S% CL. This result holds for natural choices of thepseudoscalar-quark couplings (e.g., flavor universal), which give rise to a significant enhancement of the dark matter-proton coupling with respect to the coupling to neutrons. We also find that this candidate can accommodate the observed 1-3 GeV gamma-ray excess at the Galactic center and at the same time have the correct relic density today. The model could be tested with measurements of rare meson decays, flavor changing processes, and searches for axionlike particles with mass in the MeV range.

來(lái)源出版物：Physical Review Letters, 2015, 114(1): 011301

The nongravitational interactions of dark matter in colliding galaxy clusters

Harvey, D; Massey, R; Kitching, T; et al.

Abstract:Collisions between galaxy clusters provide a test of the nongravitational forces acting on dark matter. Dark matter’s lack of deceleration in the “bullet cluster”collision constrained its self-interaction cross section σDM/m＜ 1.25 square centimeters per gram (cm2/g) [68% confidence limit (CL)] (σDM, self-interaction cross section;m, unit mass of dark matter) for long-ranged forces. Using the Chandra and Hubble Space Telescopes, we have now observed 72 collisions, including both major and minor mergers. Combining these measurements statistically, we detect the existence of dark mass at 7.6σ significance. The position of the dark mass has remained closely aligned within 5.8 ± 8.2 kiloparsecs of associated stars, implying a self-interaction cross section σDM/m＜ 0.47 cm2/g (95% CL) and disfavoring some proposed extensions to the standard model.

來(lái)源出版物：Science, 2015, 347(6229): 1462-1465

First dark matter search results from the PandaX-I experiment

Xiao, MJ; Xiao, X，Zhao, L; et al.

Abstract:We report on the first dark-matter (DM) search results from PandaX-I, a low threshold dual-phase xenon experiment operating at the China JinPing Underground Laboratory. In the 37 kg liquid xenon target with 17.4 live-days of exposure, no DM particle candidate event was found. This result sets a stringent limit for low-mass DM particles and disfavors the interpretation of previouslyreported positive experimental results. The minimum upper limit, 3.7×10-44cm2, for the spin-independent isoscalar DM-particle-nucleon scattering cross section is obtained at a DM-particle mass of 49 GeV/c2at 90% confidence level.

關(guān)鍵詞：dark matter; direct detection; xenon

來(lái)源出版物：Science China Physics, Mechanics & Astronomy, 2014, 57(11): 2024-2030

聯(lián)系郵箱：Harvey, D; david.harvey@epfl.ch

On the validity of the effective field theory for dark matter searches at the LHC

Busoni, G; De Simone, A; Morgante, E; et al.

Abstract:We discuss the limitations to the use of the effective field theory approach to study dark matter at the LHC. We introduce and study a few quantities, some of them independent of the ultraviolet completion of the dark matter theory, which quantify the error made when using effective operators to describe processes with very high momentum transfer. Our criteria indicate up to what cutoff energy scale, and with what precision, the effective description is valid, depending on the dark matter mass and couplings.

來(lái)源出版物：Physics Letters B, 2014, 728: 412-421

聯(lián)系郵箱：De Simone, A; giorgio.busoni@sissa.it

The properties of warm dark matter haloes

Lovell, MR; Frenk, CS; Eke, VR; et al.

Abstract:Well-motivated elementary particle candidates for the dark matter, such as the sterile neutrino, behave as warm dark matter (WDM). For particle masses of order a keV, free streaming produces a cutoff in the linear fluctuation power spectrum at a scale corresponding to dwarf galaxies. We investigate the abundance and structure of WDM haloes and subhaloes on these scales using high resolution cosmological N-body simulations of galactic haloes of mass similar to the Milky Way’s. On scales larger than the free-streaming cutoff, the initial conditions have the same power spectrum and phases as one of the cold dark matter (CDM) haloes previously simulated by Springel et al. as part of the Virgo consortium Aquarius project. We have simulated four haloes with WDM particle masses in the range 1.5-2.3 keV and, for one case, we have carried out further simulations at varying resolution. N-body simulations in which the power spectrum cutoff is resolved are known to undergo artificial fragmentation in filaments producing spurious clumps which, for small masses (＜ 107M⊙in our case) outnumber genuine haloes. We have developed a robust algorithm to identify these spurious objects and remove them from our halo catalogues. We find that the WDM subhalo mass functionis suppressed by well over an order magnitude relative to the CDM case for masses ＜ 109M⊙. Requiring that there should be at least as many subhaloes as there are observed satellites in the Milky Way leads to a conservative lower limit to the (thermal equivalent) WDM particle mass of～ 1.5 keV. WDM haloes and subhaloes have cuspy density distributions that are well described by NFW or Einasto profiles. Their central densities are lower for lower WDM particle masses and none of the models we have considered suffer from the “too big to fail” problem recently highlighted by Boylan-Kolchin et al.

關(guān)鍵詞：galaxies: dwarf; dark matter

來(lái)源出版物：Monthly Notices of the Royal Astronomical Society, 2014, 439 (1): 300-317

聯(lián)系郵箱：Lovell, MR; m.r.lovell@durham.ac.uk

The poker face of the Majoron dark matter model: LUX to keV line

Queiroz, FS; Sinha, K

Abstract:We study the viability of pseudo Nambu-Goldstone bosons (Majorons) arising in see-saw models as dark matter candidates. Interestingly the stability of the Majoron as dark matter is related to the scale that sets the see-saw and leptogenesis mechanisms, while its annihilation and scattering cross section off nuclei can be set through the Higgs portal. ForO(GeV)-O(TeV) Majorons, we compute observables such as the abundance, scattering cross section, Higgs invisible decay width, and emission lines and compare with current data in order to outline the excluded versus still viable parameter space regions. We conclude that the simplest Majoron dark matter models coupling through the Higgs portal, except at the Higgs resonance, are excluded by current direct detection data for Majorons lighter than 225 GeV and future runnings are expected to rule out decisively the 1 GeV-1 TeV window. Lastly, we point out that light keV-scale Majorons whose relic density is set by thermal freeze-in from sterile neutrinos can account for the keV line observed by XMM-Newton observatory in the spectrum of 73 galaxy clusters, within a see-saw model with a triplet Higgs.

來(lái)源出版物：Physics Letters B, 2014, 735: 69-74

聯(lián)系郵箱：Sinha, K; fdasilva@ucsc.edu

Cold dark matter haloes in the Planck era: evolution of structural parameters for Einasto and NFW profiles

Dutton, AA; Maccio, AV

Abstract:We present the evolution of the structure of relaxed cold dark matter (CDM) haloes in the cosmology from thePlancksatellite. Our simulations cover five decades in halo mass, from dwarf galaxies to galaxy clusters. Because of the increased matter density and power spectrum normalization the concentration-mass relation in thePlanckcosmology has a ～20 per cent higher normalization at redshiftz=0 compared toWilkinson Microwave Anisotropy Probecosmology. We confirm that CDM haloes are better described by the Einasto profile; for example, at scales near galaxy half-light radii CDM haloes have significantly steeper density profiles than implied by Navarro-Frenk-White (NFW) fits. There is a scatter of～0.2 dex in the Einasto shape parameter at fixed halo mass, adding further to the diversity of CDM halo profiles. The evolution of the concentration-mass relation in our simulations is not reproduced by any of the analytic models in the literature. We thus provide a simple fitting formula that accurately describes the evolution between redshiftsz=5 and 0 for both NFW and Einasto fits. Finally, the observed concentrations and halo masses of spiral galaxies, groups and clusters of galaxies at low redshifts are in good agreement with our simulations, suggesting only mild halo response to galaxy formation on these scales.

關(guān)鍵詞：methods: numerical; galaxies: haloes; cosmology: theory; dark matter

來(lái)源出版物：Monthly Notices of the Royal Astronomical Society, 2014, 441(4): 3359-3374

聯(lián)系郵箱：Dutton, AA; dutton@mpia.de

編輯：王微

The LHC diphoton resonance and dark matter

Mambrini, Y; Arcadi, G; Djouadi, A

A resonance with a mass of approximately 750 GeV has recently been “observed” at the LHC in its diphoton decay. If this state is not simply a statistical fluctuation which will disappear with more data, it could have important implications not only for particle physics but also for cosmology. In this note, we analyze the implications of such a resonance for the dark matter (DM). Assuming a spin-1/2 DM particle, we first verify that indeed the correct relic density can be obtained for a wide range of the particle mass and weak scale coupling, that are compatible with present data. We then show that the combination of near future direct and indirect detection experiments will allow to probe the CP-nature of the mediator resonance, i.e. discriminate whether it is a scalar or a pseudoscalar like particle.