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	<title>Hidden Dimensions</title>
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	<description>Phiphy&#039;s Physics Study Notes</description>
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		<title>Hidden Dimensions</title>
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			<item>
		<title>QFT Journal Club 2: Propagator Theory</title>
		<link>http://phiphy.wordpress.com/2009/10/08/qft-journal-club-2-propagator-theory/</link>
		<comments>http://phiphy.wordpress.com/2009/10/08/qft-journal-club-2-propagator-theory/#comments</comments>
		<pubDate>Thu, 08 Oct 2009 22:45:04 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[Communications]]></category>
		<category><![CDATA[Read them]]></category>
		<category><![CDATA[hep_th]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=96</guid>
		<description><![CDATA[Time: 10/3/2009
Speaker: James Murray

Outline:

Non-relativistic propagators in quantum mechanics.
Propagators of scalar field.
Propagators of fermion field.
The perturbative solution of propagators.

Reference:
Bjorken &#38; Drell, Relativistic Quantum Mechanics, Chapter 6.
Comments:
Only part of the comments were made in the meeting.

Propagators as Green&#8217;s Functions

The mathematical meaning of propagators are just Green&#8217;s functions of the equations of motion (EOM) of the particles or [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=96&subd=phiphy&ref=&feed=1" />]]></description>
		<wfw:commentRss>http://phiphy.wordpress.com/2009/10/08/qft-journal-club-2-propagator-theory/feed/</wfw:commentRss>
		<slash:comments>1</slash:comments>
	
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			<media:title type="html">Phiphy</media:title>
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		<item>
		<title>QFT Journal Club 1: Groups and Group Representations in Physics</title>
		<link>http://phiphy.wordpress.com/2009/09/20/qft-journal-club-1-group-and-group-representation-theory-in-physics/</link>
		<comments>http://phiphy.wordpress.com/2009/09/20/qft-journal-club-1-group-and-group-representation-theory-in-physics/#comments</comments>
		<pubDate>Mon, 21 Sep 2009 02:51:43 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[Communications]]></category>
		<category><![CDATA[hep_th]]></category>
		<category><![CDATA[math]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=80</guid>
		<description><![CDATA[Time: 9/19/2009
Speaker: Chris Brust
Outline:

Definition of groups: 4 axioms.
Finite groups: defined by a multiplication tables.
Example: Permutation group 
Group representations: mapping a group to a set of matrices.
trivial rep, faithful rep, reducible and irreducible rep, unitary rep
Example: 3 (and the only 3) irreducible rep of , 1 faithful but reducible rep of 
Lie groups: continuous groups which [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=80&subd=phiphy&ref=&feed=1" />]]></description>
		<wfw:commentRss>http://phiphy.wordpress.com/2009/09/20/qft-journal-club-1-group-and-group-representation-theory-in-physics/feed/</wfw:commentRss>
		<slash:comments>1</slash:comments>
	
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			<media:title type="html">Phiphy</media:title>
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		<item>
		<title>Discussions on Entropy</title>
		<link>http://phiphy.wordpress.com/2009/09/11/on-entropy/</link>
		<comments>http://phiphy.wordpress.com/2009/09/11/on-entropy/#comments</comments>
		<pubDate>Sat, 12 Sep 2009 03:39:10 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[Communications]]></category>
		<category><![CDATA[stats]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=67</guid>
		<description><![CDATA[Information entropy is in fact a more fundamental definition than our familiar Baltzmann entropy in stat mech.
When we use Boltzmann energy , where W is the total number of microscopic states of the system with a given macroscopic state, we assume that all microscopic states has the same probability. This is true for most thermal [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=67&subd=phiphy&ref=&feed=1" />]]></description>
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		<slash:comments>0</slash:comments>
	
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			<media:title type="html">Phiphy</media:title>
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	</item>
		<item>
		<title>Scientist: Four golden lessons (ZZ)</title>
		<link>http://phiphy.wordpress.com/2009/07/17/scientist-four-golden-lessons-zz/</link>
		<comments>http://phiphy.wordpress.com/2009/07/17/scientist-four-golden-lessons-zz/#comments</comments>
		<pubDate>Fri, 17 Jul 2009 13:57:56 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[Read them]]></category>
		<category><![CDATA[the way of research]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=57</guid>
		<description><![CDATA[These are bloody correct lessons.
http://www.nature.com/nature/journal/v426/n6965/full/426389a.html
Steven Weinberg
When I received my undergraduate degree — about a hundred years ago — the physics literature seemed to me a vast, unexplored ocean, every part of which I had to chart before beginning any research of my own. How could I do anything without knowing everything that had already been [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=57&subd=phiphy&ref=&feed=1" />]]></description>
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		<slash:comments>0</slash:comments>
	
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			<media:title type="html">Phiphy</media:title>
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		<item>
		<title>杂记</title>
		<link>http://phiphy.wordpress.com/2008/10/11/%e6%9d%82%e8%ae%b0/</link>
		<comments>http://phiphy.wordpress.com/2008/10/11/%e6%9d%82%e8%ae%b0/#comments</comments>
		<pubDate>Sat, 11 Oct 2008 05:31:18 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[My progress]]></category>
		<category><![CDATA[the way of research]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=35</guid>
		<description><![CDATA[一个人想法的多少难道是随着他的知识增长成U型变化趋势的吗？以前只知道皮毛的时候想法很多很大胆，跟民科一样，现在目不暇接地学了一堆东东却似乎什么都不敢想了，因为每一个想法似乎不是有人做过就是马上会被否定掉，经历了太多这样的情况就开始变得麻木了。真是有些担心，不知道学通之后真正有用的想法能不能多起来。就算做model builder, 我的目标也是总工程师。
今年的诺贝尔奖跟我正在关心的东西关系不小，如果有时间我会自己总结一个review,关于对称性自发破缺和费米子混合问题。
美国的高能实验快进入冬天了。美国政府的科研经费申请政策太弱智了，一个大型项目每年都要重新审批，砸了无数钱建到一半都能扔下，不想出钱又狂浪费钱，目光短浅的严重表现。现在好了，金融危机一闹彻底没戏了。
LHC最早在明年4月就能出第一批数据了，而额外维的引力子貌似是需要数据最少的。RS首当其冲啊，要死的话就是死得最早的。这样也好，省得我在上面白白浪费青春。
       <img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=35&subd=phiphy&ref=&feed=1" />]]></description>
		<wfw:commentRss>http://phiphy.wordpress.com/2008/10/11/%e6%9d%82%e8%ae%b0/feed/</wfw:commentRss>
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			<media:title type="html">Phiphy</media:title>
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	</item>
		<item>
		<title>LHC Physics Mini Workshop</title>
		<link>http://phiphy.wordpress.com/2008/05/16/lhc-physics-mini-workshop/</link>
		<comments>http://phiphy.wordpress.com/2008/05/16/lhc-physics-mini-workshop/#comments</comments>
		<pubDate>Fri, 16 May 2008 22:10:46 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[Communications]]></category>
		<category><![CDATA[hep_ph]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=34</guid>
		<description><![CDATA[LHC is coming soon, every one in particle physics is excited. And you can smell in the air how crazily LHC-driven they are. The mini workshop of LHC physics was held at UMD, for model builders to discuss the phenomenology of some model which are expected to be tested on LHC.
Quirks:
Markus Luty and Roni Harnik
Both [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=34&subd=phiphy&ref=&feed=1" />]]></description>
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		<slash:comments>0</slash:comments>
	
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			<media:title type="html">Phiphy</media:title>
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		<item>
		<title>LHC &#8211; The 0th Year</title>
		<link>http://phiphy.wordpress.com/2008/05/09/lhc-the-0th-year/</link>
		<comments>http://phiphy.wordpress.com/2008/05/09/lhc-the-0th-year/#comments</comments>
		<pubDate>Sat, 10 May 2008 01:37:15 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[What's going on]]></category>
		<category><![CDATA[hep_ex]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=33</guid>
		<description><![CDATA[End June:
Machine cold
Expt beampipe bakeout finished
Mid-July: 
Experiments configured ready for beam
Patrol of tunnel and caverns
Controlled access only
End-July:
First injection
Commissioning with beam, including at some point
few hours collisions at 900 GeV cm

End Sept:
Collisions at 10 TeV..2008 physics run.
End Nov??
Winter shutdown: commission to 14 TeV.
       <img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=33&subd=phiphy&ref=&feed=1" />]]></description>
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			<media:title type="html">Phiphy</media:title>
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		<item>
		<title>Dark Energy &#8211; Ten Years</title>
		<link>http://phiphy.wordpress.com/2008/05/07/accelerating-universe-ten-years/</link>
		<comments>http://phiphy.wordpress.com/2008/05/07/accelerating-universe-ten-years/#comments</comments>
		<pubDate>Thu, 08 May 2008 01:00:06 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[Communications]]></category>
		<category><![CDATA[cosmology]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=28</guid>
		<description><![CDATA[There is a symposium held by STScI to review the ten years&#8217; progress in cosmology after the discovery of accelerating expansion of the universe. I missed some very important talks on Monday, not only because one of the speakers was Witten   but also it was the only series of physical topics (rather than [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=28&subd=phiphy&ref=&feed=1" />]]></description>
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		<slash:comments>0</slash:comments>
	
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			<media:title type="html">Phiphy</media:title>
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		<item>
		<title>概率问题</title>
		<link>http://phiphy.wordpress.com/2008/04/30/%e6%a6%82%e7%8e%87%e9%97%ae%e9%a2%98/</link>
		<comments>http://phiphy.wordpress.com/2008/04/30/%e6%a6%82%e7%8e%87%e9%97%ae%e9%a2%98/#comments</comments>
		<pubDate>Wed, 30 Apr 2008 13:27:31 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[Sparks of the mind]]></category>
		<category><![CDATA[math]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=25</guid>
		<description><![CDATA[一个运动员在药检时结果呈阳性（即怀疑服用违禁药品）。药品检验器材的厂方提供的信息是：在阳性结果里有1%的失误率，在阴性结果里有20%的失误率。在 已经受检的20000名运动员中，有300人结果呈阳性。请问这位运动员确实服用了违禁药品的几率是多大？（提示：不是99%，我也搞不懂为什么）。
Update:
这是一个条件概率问题。关键在如何理解厂方信息。所谓“阳性结果里有1%的失误率”是什么意思？是不是说一个人如果被检验成阳性，他吃药的几率就是99%？从字面理解好像是这样，但仔细想想，这个数据不是厂方可以提供的，因为要想得到这个数据，我们需要一堆事先并不知道是否吃药的样本人群，让他们去测验，拿到结果后再跟他们是否吃药的真实情况比较，但是否吃药显然跟整个人群的吃药率有关，因此这个量不是能够独立测量的。但另一个量是只跟仪器有关，跟人群吃药率无关的，那就是一个事先确定吃药或没吃药的人的检查结果，厂方正是用这个方法来定义和测量仪器灵敏度的。用数学语言说，如果用P(A&#124;B)表示条件B成立的情况下A的概率，那么厂方提供的是P(阳性&#124;未吃药）=1%，P(阴性&#124;吃药)=20%，而我们想要求的是P(吃药&#124;阳性）。最后答案是32%。
       <img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=25&subd=phiphy&ref=&feed=1" />]]></description>
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			<media:title type="html">Phiphy</media:title>
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		<title>New physics seen?</title>
		<link>http://phiphy.wordpress.com/2008/03/06/new-physics-seen/</link>
		<comments>http://phiphy.wordpress.com/2008/03/06/new-physics-seen/#comments</comments>
		<pubDate>Thu, 06 Mar 2008 22:00:20 +0000</pubDate>
		<dc:creator>Phiphy</dc:creator>
				<category><![CDATA[What's going on]]></category>
		<category><![CDATA[hep_ex]]></category>

		<guid isPermaLink="false">http://phiphy.wordpress.com/?p=24</guid>
		<description><![CDATA[The UTfit group claimed that they find the &#8216;first evidence&#8217; of new physics in  transition.By combining analysis of all the experiments on  mixing, the CP violation phase is 3 deviated from both SM and MFV(minimum flavor violation). Sounds thrilling, but we still need to wait and see.
       [...]<img alt="" border="0" src="http://stats.wordpress.com/b.gif?host=phiphy.wordpress.com&blog=1506939&post=24&subd=phiphy&ref=&feed=1" />]]></description>
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		<slash:comments>0</slash:comments>
	
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